forget: cleanup the output for an inexact case match on icasefs
Previously, specifying a file name but not matching the dirstate case yielded
the following, even though the file was actually removed:
$ hg forget capsdir1/capsdir/abc.txt
not removing capsdir\a.txt: file is already untracked
removing CapsDir\A.txt
[1]
This change doesn't appear to cause any extra filesystem accesses, even if a
nonexistant file is specified.
If a directory is specified without a case match, it is (and was previously)
still silently ignored.
(binary:application/octet-stream)