keyword: move common code out of commit condition

hgext/keyword.py

@@ -165,14 +165,12 b' class kwtemplater(object):'
 
     def overwrite(self, node, expand, files):
         '''Overwrites selected files expanding/shrinking keywords.'''
-        if node is not None:     # commit
             ctx = self.repo[node]
             mf = ctx.manifest()
+        if node is not None:     # commit
             files = [f for f in ctx.files() if f in mf]
             notify = self.ui.debug
         else:                    # kwexpand/kwshrink
-            ctx = self.repo[None]
-            mf = ctx.manifest()
             notify = self.ui.note
         candidates = [f for f in files if self.iskwfile(f, ctx.flags)]
         if candidates: