1. Summarise the issue (what were doing, what went wrong?)

If you attempt to apply a patch with a filename containing colons, the
path is interpreted as a ssh (I think) path:

     % darcs apply stash:foo.dpatch 

     darcs failed:  (scp) failed to fetch: stash:foo.dpatch/_darcs/

It does exist:

     % ls -l stash:foo.dpatch 
     -rw-rw-r-- 1 owen owen 367 Oct 31 11:57 stash:foo.dpatch

and moving it, then applying, works:

     % mv stash:foo.dpatch stash.dpatch
     % darcs apply stash.dpatch
     Finished applying...

2. What behaviour were you expecting instead?

Darcs shouldn't blindly attempt to treat filenames containing colons as
ssh urls...!

3. What darcs version are you using? (Try: darcs --exact-version)

2.9.5 (+ 34 patches)

4. What operating system are you running?

Ubuntu x86_64

There is no other way to distinguish between remote ssh paths and 
local paths. scp and rsync have the same issue.