localrepo.commit: normalize commit message even for rawcommit.

This normalization consists of:
- stripping trailing whitespace
- always using "\n" as the line separator

I think the main reason rawcommit was skipping this normalization was
an attempt to preserve hashes during an hg->hg conversion.

While this is a nice goal, it's not particularly interesting in
practice.  Since SHA-1 is so strong, the only safe way to do it is to
have absolutely identical revisions.  But:

- if the original revision was created with a recent version of hg,
  the commit message will be the same, with or without that
  normalization

- if it was created with an ancient version of hg that didn't do any
  normalization, even if the commit message is identical, the file list
  in the changelog is likely to be different (e.g. no removed files),
  and there were some old issues with e.g. extra file merging, which
  will end up changing the hash anyway

- in any case, if one *really* has to preserve hashes, it's easier
  (and faster) to fake a partial conversion using something like:

  hg clone -U -r rev orig-repo new-repo
  hg -R new-repo log --template '#node# #node#\n' > new-repo/.hg/shamap

Additionally, we've had some reports of problems arising from this lack
of normalization - e.g. issue871, and a user that was wondering why
hg export/hg import was not preserving hashes when there was nothing
unusual going on (it was just import doing the normalization that had
been skipped).

This also means that it's even more unlikely to get identical revisions
when going $VCS->hg->$VCS.

mercurial/localrepo.py

@@ -883,11 +883,10 b' class localrepository(repo.repository):'
             if branchname:
                 extra["branch"] = branchname
 
-            if use_dirstate:
                 lines = [line.rstrip() for line in text.rstrip().splitlines()]
                 while lines and not lines[0]:
                     del lines[0]
-                if not lines:
+            if not lines and use_dirstate:
                     raise util.Abort(_("empty commit message"))
                 text = '\n'.join(lines)
 

tests/test-convert-git.out

@@ -10,10 +10,10 b' 3 t3'
 2 t4.1
 1 t4.2
 0 Merge branch other
-changeset:   5:c6d72c98aa00
+changeset:   5:4ab1af49a271
 tag:         tip
-parent:      3:a18bdfccf429
-parent:      4:48cb5b72ce56
+parent:      3:0222ab0998d7
+parent:      4:5333c870e3c2
 user:        test <[e-mail]>
 date:        Mon Jan 01 00:00:15 2007 +0000
 files:       a