I am working with a linux source tree pulled through git.  I couldn't figure
out the user interface of git to simply add and record one file, so I gave up
and decided to use darcs instead:

KERN yumyum:/usr/src/linux$ darcs init
KERN yumyum:/usr/src/linux$ darcs add .config
darcs: takeLock //_darcs/lock in /: atomic_create //_darcs/lock in /: permission denied (Permission denied)

What the heck?  (There is a /_darcs, but it is not writable by me.)

After some sleuthing I've learned that if I mv .git .git-aside, then darcs
works as normal.  I just have to remember to mv it back when I want to use git.

Regards,

Zooko

Suggested fix sent to darcs-devel.

Hmm, there's another bug in your output which is actually more serious --
Darcs should distinguish between maybeIdentifyRepository failing because
we're not in a repo (in which case we should recurse upwards), and its
failing for a good reason.

Retitling, reopening, unsassigning.  And stuff.

A look at the code for maybeIdentifyRepository suggests that this is fixed. 
Also, I removed the git support, so this particular issue won't arise.