manifestdict: inline _intersectfiles()

The _intersectfiles() method is only called from one place, it's
pretty short, and its caller has to be aware when it's appropriate to
call it (when the number of files in the matcher is not too large), so
let's inline it.

mercurial/manifest.py

@@ -198,17 +198,6 b' class manifestdict(object):'
     def keys(self):
         return list(self.iterkeys())
 
-    def _intersectfiles(self, files):
-        '''make a new lazymanifest with the intersection of self with files
-
-        The algorithm assumes that files is much smaller than self.'''
-        ret = manifestdict()
-        lm = self._lm
-        for fn in files:
-            if fn in lm:
-                ret._lm[fn] = lm[fn]
-        return ret
-
     def filesnotin(self, m2):
         '''Set of files in this manifest that are not in the other'''
         files = set(self)
@@ -265,7 +254,12 b' class manifestdict(object):'
         files = match.files()
         if (len(files) < 100 and (match.isexact() or
             (not match.anypats() and util.all(fn in self for fn in files)))):
-            return self._intersectfiles(files)
+            m = manifestdict()
+            lm = self._lm
+            for fn in match.files():
+                if fn in lm:
+                    m._lm[fn] = lm[fn]
+            return m
 
         m = manifestdict('')
         m._lm = self._lm.filtercopy(match)