This patch isn't quite there, it breaks the test for issue2066. I'll see
what I can work out - it appears that shell-rm'd files don't appear in
readRecordedAndPending's output...
This patch will be fine, when issue2212 has been fixed. Currently, darcs
will update pending with rm'd files, when adding distinct files. This
causes the issue2066 test to fail, since darcs thinks that one of the
files has been deleted in pending.