plan9: mkfile and 9diff fixes This patch deals with an unnecessary backslash in 9diff and improper quoting in the contrib mkfile.

subrepo/svn: cache _wcrev() value in merge()

subrepo/svn: fix checked out rev number retrieval (issue2968) The initial version was to take the "Revision" field from svn info. It works but produces false positive when parent paths are being moved or unrelated changes are being committed, causing it to change while the svn checkout itself remains the same. To avoid spurious commit, we took "Revision" and "Last Changed Rev" for general comparison and kept the latter to answer "what is your revision?" question. This is better but fails when the subrepo path exists at "Revision" but not at "Last Changed Rev". This patch adds a check for this, and returns "Revision" if the path does not exist. We try to avoid doing this as much as possible at it implies an extra, *remote* call.

amend: fix copy records handling (issue3410) Messing with the dirstate before the intermediate commit seems error prone. Instead, commit and recompute the copies with copies.pathcopies(), then use that with commitctx(). Since copies.pathcopies() does not support file replacement very well, the whole .renamed() condition in samefile() is removed and the "file replacement caused by differing copy source" effect is discarded. Test shamelessly stolen from Idan Kamara <idankk86@gmail.com>

test-commit-amend: exhibit an --amend weirdness The weirdness is --amend let you replace one file with another with same data and flags if the new file copy record differ from the one in the parent revision. In theory, there is no problem with this kind of thing, subversion supports it, but here we see log and status disagree. The reason is log reads the copy record from the filelog, while status calls copies.pathcopies() which eventually invokes some expensiveness argument to discard this case (copies.py, _forwardcopies(), line 132). Since the next patch will side with pathcopies(), I prefer to call this behaviour a bug.

localrepo: add setparents() to adjust dirstate copies (issue3407) The fix introduced in eab9119c5dee was only partially successful. It is correct to turn dirstate 'm' merge records into normal/dirty ones but copy records are lost in the process. To adjust them as well, we need to look in the first parent manifest to know which files were added and preserve only related records. But the dirstate does not have access to changesets, the logic has to moved at another level, in localrepo.