merge: hoist some working manifest logic out of merge loop

mercurial/merge.py

@@ -116,8 +116,12 b' def update(repo, node, branchmerge=False'
     umap = dict.fromkeys(unknown)
 
     for f in added + modified + unknown:
-        mw[f] = None
-        if f in m1: mw[f] = "" # distinguish between changed and new
+        mw[f] = ""
+        # is the wfile new and matches m2?
+        if (f not in m1 and f in m2 and
+            not repo.file(f).cmp(m2[f], repo.wread(f))):
+            mw[f] = m2[f]
+
         mw.set(f, util.is_exec(repo.wjoin(f), mw.execf(f)))
 
     for f in deleted + removed:
@@ -139,11 +143,6 b' def update(repo, node, branchmerge=False'
         if f in m2:
             s = 0
 
-            # is the wfile new and matches m2?
-            if mw[f] == None:
-                if not repo.file(f).cmp(m2[f], repo.wread(f)):
-                    n = m2[f]
-
             # are files different?
             if n != m2[f]:
                 a = ma.get(f, nullid)