I have a partial repository I can't checkpoint (this is a get --partial of
http://darcs.haskell.org/ghc-6.6/ghc; it also happens on the real thing):

igloo@monk:~/fiddle$ darcs check
Applying patch 733 of 733... done.
The repository is consistent!
igloo@monk:~/fiddle$ darcs optimize --checkpoint
Checkpointing tag:
Mon Feb  5 06:38:15 PST 2007  q
  tagged t

Fail: bug in darcs!
fromJust error at DarcsRepo.lhs:525 compiled 13:42:37 Sep 12 2006
Please report this to bugs@darcs.net,
If possible include the output of 'darcs --exact-version'.
igloo@monk:~/fiddle$ darcs tag --checkpoint -m foo

Fail: bug in darcs!
fromJust error at DarcsRepo.lhs:514 compiled 13:42:37 Sep 12 2006
Please report this to bugs@darcs.net,
If possible include the output of 'darcs --exact-version'.
igloo@monk:~/fiddle$ darcs check
Applying patch 734 of 734... done.
The repository is consistent!
igloo@monk:~/fiddle$ darcs --exact-version
darcs compiled on Sep 12 2006, at 13:44:57
# configured Fri Jun 16 14:55:21 EDT 2006
./configure --no-create --no-recursion

Context:

[TAG 1.0.8
Tommy Pettersson <ptp@lysator.liu.se>**20060616160213] 
igloo@monk:~/fiddle$

It doesn't work even with the lastest development version too (i have the same 
problem on the same repository).

Checkpointing tag:
Tue Apr 10 17:56:30 CEST 2007  Dario Meloni <mellon85@gmail.com>
  tagged tesi
darcs: bug in darcs!
fromJust error at DarcsRepo.lhs:533 compiled 11:10:56 Apr 12 2007
Please report this to bugs@darcs.net,
If possible include the output of 'darcs --exact-version'.


darcs compiled on Apr 12 2007, at 11:12:59
# configured Wed Jan 17 14:27:22 EST 2007
./configure --no-create --no-recursion

Context:

[update web page for new mailing list server.
David Roundy <droundy@darcs.net>**20070116162930] 

[fix spelling errors in comments
Benedikt Schmidt <beschmi@cloaked.de>**20061222020037] 

[Fix ssh.sh test.
Dave Love <fx@gnu.org>**20061218223442] 

[add warning about ALL and obliterate --all to documentation
Tommy Pettersson <ptp@lysator.liu.se>**20061219180302] 

[Fix includes in External.hs.
Dave Love <fx@gnu.org>**20061218224158
 You can't put comments before {-# INCLUDE ...
] 

[add test for reverting removed directory
Tommy Pettersson <ptp@lysator.liu.se>**20061108202344] 

[Improve error messages in push_cmd
chevalier@alum.wellesley.edu**20061207040701
 
 I ran into this because MSYS was munging my repository directory in a
 horrible way. This resulted in a bad repo directory getting passed into
 darcs, which resulted in a fromJust error, which we all know makes the
 baby Jesus cry. So, I at least refactored the code to give a better
 error message, though there may well be a better solution.
] 

[Implement prettyException.
Juliusz Chroboczek <jch@pps.jussieu.fr>**20061218025440] 

[Simplify common libcurl errors.
Juliusz Chroboczek <jch@pps.jussieu.fr>**20061218025419] 

[fix issue369 by failing if quickcheck isn't available
David Roundy <droundy@darcs.net>**20061218021545] 

[Don't QP-encode bundles when pushing locally.
Juliusz Chroboczek <jch@pps.jussieu.fr>**20061218002533] 

[Make darcs push QP-encode the bundle before transferring.
Juliusz Chroboczek <jch@pps.jussieu.fr>**20061217234635
 This should hopefully fix issues with scp/sftp corrupting bundles in transit.
] 

[Adapt callers to new calling convention for make_email.
Juliusz Chroboczek <jch@pps.jussieu.fr>**20061217234608
 Use Just at the right places.
] 

[Make arguments to make_email optional.
Juliusz Chroboczek <jch@pps.jussieu.fr>**20061217234501
 Makes contents and filename optional.  If they are omitted, we still
 generate a conforming MIME message.
] 

[add test for get --tag and pending
Tommy Pettersson <ptp@lysator.liu.se>**20061211192821] 

[add new test related to issue262.
David Roundy <droundy@darcs.net>**20061217221041
 This issue seems to already have been fixed.
] 

[Added test for reverting an unrecorded add
edwin.thomson@businesswebsoftware.com**20061215180047] 

[add test that sigPIPE doesn't make darcs fail.
David Roundy <droundy@darcs.net>**20061209230155] 

[make it an error to "put" into a preexisting directory.
David Roundy <droundy@darcs.net>**20061203205826
 This changes darcs' behavior I believe for the better.  Often one could be
 tempted to try to put into a directory, expecting to have the repository
 created as a subdirectory there, and it seems confusing (confused me) to
 have instead the repository contents mingled with whatever was already in
 that directory.  Put should behave like get in this regard, in that it
 shouldn't mix the new repo with a preexisting directory.
] 

[adapt test sametwice to new obliterate --all feature
Tommy Pettersson <ptp@lysator.liu.se>**20061130132058] 

[Adapt test perms.sh to obliterate --all feature.
Eric Kow <eric.kow@gmail.com>**20061209200625] 

[use impossible to document impossible case in Repair.
David Roundy <droundy@darcs.net>**20061204152854] 

[fix for Issue111, obliterate --all
David Roundy <droundy@darcs.net>**20061129164016
 This is a patch to implement the wishless item Issue111,
 which asks for an --all option to obliterate.  The idea is
 that you might use the --patches flag to select a bunch of
 patches and not want to have to say yess to all of them.
 
 For good measure, I also added it to unpull and unrecord.
] 

[catch exceptions in stdout_is_a_pipe
Simon Marlow <simonmar@microsoft.com>**20061129160620] 

[hFlush after "waiting for lock" message
Simon Marlow <simonmar@microsoft.com>**20061129160342
 On Windows, stdout isn't always in line-buffered mode, but we really
 want to see the message about waiting for a lock quickly.  Mostly
 because ^C isn't always caught properly on Windows and lock files are
 often left behind, but that's another storey...
 
] 

[add explicit import list
Simon Marlow <simonmar@microsoft.com>**20061129160144] 

[ignore failure from hSetBuffering
Tommy Pettersson <ptp@lysator.liu.se>**20061117221424
 This affects:
   issue41      Doesn't like pasted text.
   issue94      Crash on bogus input
   issue146     hSetBuffering: invalid argument
   issue318     buffering error of darcs record under bash/cmd.exe
 It doesn't necessarily "fix" anything. It prevents darcs from quiting,
 instead continuing with perhaps an undesirable buffering mode, which may or
 may not be better ... or worse.
] 

[Hard link support on Windows
Simon Marlow <simonmar@microsoft.com>*-20061204162040
 This works only on NTFS filesystems.  Also it requires Windows 2000 or
 later; this may or may not be acceptable, I'll leave that up to the
 darcs maintainers to decide.
] 

[Hard link support on Windows
Simon Marlow <simonmar@microsoft.com>**20061204162040
 This works only on NTFS filesystems.  Also it requires Windows 2000 or
 later; this may or may not be acceptable, I'll leave that up to the
 darcs maintainers to decide.
] 

[Canonize Kirsten Chevalier.
Kirsten Chevalier <chevalier@alum.wellesley.edu>**20061217025004
 
 Added my name to the list of authors who originally only submitted an email
 address.
 
] 

[Documentation only - clarify meaning of --from and --author
Kirsten Chevalier <chevalier@alum.wellesley.edu>**20061217024927
   
 Clarified the meaning of --from and --author. I had assumed that these
 options also set the From: address on the email sent by "darcs sent".  Of
 course they don't, but it's better to make this clear.
 
] 

[Do _not_ allow escaped quotes in `quoted'.
Eric Kow <eric.kow@loria.fr>**20061030064531
 
 This undoes the patch by Dave Love: Allow escaped quotes in `quoted'.
 The immediate problem is that it breaks make_changelog (because one of
 Tommy's entries matches on a backslash).  This feature might need more
 discussion before we include it (or not).
 
] 

[Replace tabs with spaces (escaped quotes in PatchMatch).
Eric Kow <eric.kow@loria.fr>**20061023192003] 

[Allow escaped quotes in `quoted'.
Dave Love <fx@gnu.org>**20060716193940] 

[Rename ssh_test to ssh.sh (for shell harness).
Eric Kow <eric.kow@gmail.com>**20061121141101
 
 Note that you must set environment variables for it do anything
 useful (namely REMOTE=you@someserver); something like the following
 should work:
   REMOTE=me@192.168.2.3 make test
 
 You need to be using public key authentication to have a fully
 automated test.
 
] 

[Overhaul and improve automation of ssh_test.
Eric Kow <eric.kow@gmail.com>**20061121141802
 
 * Now quits if you don't supply REMOTE; does not have any
   silly default values
 * Options now passed in through environment variables, so:
     NO_CONTROL_MASTER=1 REMOTE=me@192.168.2.12 ./ssh_test
 * Performs some automated success checks (which means that
   it should be possible to use this from the harness if you
   have ssh-agent running)
 * Performs darcs send test
 * Does not try to pass darcs-ssh flags (like --disable-ssh-cm)
   to non-ssh-using commands like record
 
] 

[Add a semi-automated test for SSH-related things.
Eric Kow <eric.kow@gmail.com>**20061110110801
 
 Testing SSH stuff is tricky in that (1) you need some place to connect
 to and (2) you often want to make sure that the user interactions work
 out right.  But it can't hurt to script away the boring stuff so that
 you are naturally encouraged to test things out more thoroughly.
] 

[remove link to obsolete mirror of kernel repo.
David Roundy <droundy@darcs.net>**20061212012644] 

[Remove raw_mode functions from atomic_create.h.
Eric Kow <eric.kow@gmail.com>**20061008202738
 
 It seems these were once implemented in compat.c and have since been
 reimplemented in Haskell by Ian Lynagh on 2005-07-30.  These appear to
 just be leftover declarations in the C header.
 
] 

[Add make rules for tags files.
Dave Love <fx@gnu.org>**20061113213923] 

[configure should fail if a required module isn't present.
David Roundy <droundy@darcs.net>**20061128024557] 

[look for --disable-ssh-cm in defaults files (issue351)
Tommy Pettersson <ptp@lysator.liu.se>**20061117180942] 

[Define infodepspatch locally in AmendRecord instead of exporting it from Patch
edwin.thomson@businesswebsoftware.com**20061121093332
 
] 

[Amending a patch doesn't remove explicit dependencies
edwin.thomson@gmail.com**20061110222837] 

[Make libcurl use any http authentication.
Tobias Gruetzmacher <darcs@portfolio16.de>**20061118230406
 This let darcs use repositories protected with digest authentication.
] 

[Support darcs send --disable-ssh-cm.
Eric Kow <eric.kow@loria.fr>**20061121134158] 

[Redirect stderr to Null when exiting SSH control master.
Eric Kow <eric.kow@loria.fr>**20061118212115
 
 This suppresses the output
 * Pseudo-terminal will not be allocated because stdin is not a terminal.
   (result of redirecting stdin from /dev/null)
 * Exit request sent.
   (seems to be normal output. Seems also that there is no way to suppress
    this; -q does not do the job, for example)
 
] 

[Fix curses stuff, especially on Solaris 10.
Dave Love <fx@gnu.org>**20061120171211] 

[Canonize Edwin Thomson.
Eric Kow <eric.kow@gmail.com>**20061118174454] 

[Annotate various boring patterns.
Dave Love <fx@gnu.org>**20061113225701] 

[TAG 1.0.9rc2
Tommy Pettersson <ptp@lysator.liu.se>**20061116140351]

I just submitted a regression test update to "partial.sh" which demonstrates
that this bug is "resolved in unstable" using Darcs 2 and a darcs-2 format
repository.