match: fix subtle error in _buildmatch

The trailing comma was causing a ValueError.  See
https://bitbucket.org/tortoisehg/thg/issue/132

mercurial/match.py

@@ -254,7 +254,7 b' def _buildmatch(pats, tail):'
         l = len(pats)
         if l < 2:
             raise
-        pata, a = _buildmatch(pats[:l//2], tail),
+        pata, a = _buildmatch(pats[:l//2], tail)
         patb, b = _buildmatch(pats[l//2:], tail)
         return pat, lambda s: a(s) or b(s)
     except re.error: