bookmarks: recognize the current bookmark when the local encoding isn't UTF-8

The current bookmark is stored in bookmark.current, supposingly in UTF-8.
But the call to encoding.fromlocal() is missing, therefore Hg is not able
to recognize the current bookmark in the case that bookmark uses
characters of which the bit stream is different between local encoding
and UTF-8.
For example, the Chinese version of Windows cmd uses gbk(cp936), not UTF-8.
Therefore I won't be able to make a Chinese bookmark current.

By wrapping mark in a encoding.fromlocal() call, the problem is solved.

mercurial/bookmarks.py

@@ -114,7 +114,7 b' def setcurrent(repo, mark):'
     wlock = repo.wlock()
     try:
         file = repo.opener('bookmarks.current', 'w', atomictemp=True)
-        file.write(mark)
+        file.write(encoding.fromlocal(mark))
         file.rename()
     finally:
         wlock.release()