cmdutil.commit: use relative paths in the error messages
This is more consistent with other error messages and requires
less makeup in test-commit and test-symlink-basic.
adding a
adding b
pulling from ../a
searching for changes
warning: repository is unrelated
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
C b