localrepo: make "undofiles()" return list of tuples "(vfs, relative filename)"

Before this patch, "localrepository.undofiles()" returns list of
absolute filename of undo files.

This patch makes it return list of tuples "(vfs, relative filename)"
to access undo files via vfs.

This patch also changes "repair.strip()", which is the only user of
"localrepository.undofiles()".

mercurial/localrepo.py

@@ -862,7 +862,7 b' class localrepository(object):'
                 (self.svfs, 'journal.phaseroots'))
 
     def undofiles(self):
-        return [vfs.join(undoname(x)) for vfs, x in self._journalfiles()]
+        return [(vfs, undoname(x)) for vfs, x in self._journalfiles()]
 
     def _writejournal(self, desc):
         self.opener.write("journal.dirstate",

mercurial/repair.py

@@ -157,12 +157,13 b' def strip(ui, repo, nodelist, backup="al'
                 os.unlink(chgrpfile)
 
         # remove undo files
-        for undofile in repo.undofiles():
+        for undovfs, undofile in repo.undofiles():
             try:
-                os.unlink(undofile)
+                undovfs.unlink(undofile)
             except OSError, e:
                 if e.errno != errno.ENOENT:
-                    ui.warn(_('error removing %s: %s\n') % (undofile, str(e)))
+                    ui.warn(_('error removing %s: %s\n') %
+                            (undovfs.join(undofile), str(e)))
 
         for m in updatebm:
             bm[m] = repo[newbmtarget].node()