tests/test-inherit-mode.out

prepush: add more precise error messages

Part of the patch is from [e-mail]

- indicate the branch name where there are multiple heads
- give better advice when hitting a possible race, where new heads are added
  between discovery and the call to branchmap(). In that case, asking the user
  to merge isn't helpful, since only remote has the changes.

% before commit
% store can be written by the group, other files cannot
% store is setgid
00700 ./.hg/
00600 ./.hg/00changelog.i
00600 ./.hg/requires
00770 ./.hg/store/

% after commit
% working dir files can only be written by the owner
% files created in .hg can be written by the group
% (in particular, store/**, dirstate, branch cache file, undo files)
% new directories are setgid
00700 ./.hg/
00600 ./.hg/00changelog.i
00660 ./.hg/dirstate
00660 ./.hg/last-message.txt
00600 ./.hg/requires
00770 ./.hg/store/
00660 ./.hg/store/00changelog.i
00660 ./.hg/store/00manifest.i
00770 ./.hg/store/data/
00770 ./.hg/store/data/dir/
00660 ./.hg/store/data/dir/bar.i
00660 ./.hg/store/data/foo.i
00660 ./.hg/store/fncache
00660 ./.hg/store/undo
00660 ./.hg/undo.branch
00660 ./.hg/undo.dirstate
00700 ./dir/
00600 ./dir/bar
00600 ./foo

% before push
% group can write everything
00770 ../push/.hg/
00660 ../push/.hg/00changelog.i
00660 ../push/.hg/requires
00770 ../push/.hg/store/

% after push
% group can still write everything
00770 ../push/.hg/
00660 ../push/.hg/00changelog.i
00660 ../push/.hg/branchheads.cache
00660 ../push/.hg/requires
00770 ../push/.hg/store/
00660 ../push/.hg/store/00changelog.i
00660 ../push/.hg/store/00manifest.i
00770 ../push/.hg/store/data/
00770 ../push/.hg/store/data/dir/
00660 ../push/.hg/store/data/dir/bar.i
00660 ../push/.hg/store/data/foo.i
00660 ../push/.hg/store/fncache
00660 ../push/.hg/store/undo
00660 ../push/.hg/undo.branch
00660 ../push/.hg/undo.dirstate