copies: teach copies about dirstate.copies

When we're using copies() to find changes between the working directory and
its first parent for diff/status/etc., use dirstate.copies() directly.

This avoids doing a full statwalk for simple diffs (issue1090) and
removes a special case from the status command.

mercurial/commands.py

@@ -2644,20 +2644,18 def status(ui, repo, *pats, **opts):
     changestates = zip(states, 'MAR!?IC', stat)
 
     if (opts['all'] or opts['copies']) and not opts['no_status']:
-        if opts.get('rev') == []:
-            # fast path, more correct with merge parents
-            copy = repo.dirstate.copies()
-        else:
             ctxn = repo.changectx(nullid)
             ctx1 = repo.changectx(node1)
             ctx2 = repo.changectx(node2)
+        added = stat[1]
             if node2 is None:
+            added = stat[0] + stat[1] # merged?
                 ctx2 = repo.workingctx()
             for k, v in copies.copies(repo, ctx1, ctx2, ctxn)[0].items():
-                if v in stat[1]:
+            if k in added:
+                copy[k] = v
+            elif v in added:
                     copy[v] = k
-                elif k in stat[1]:
-                    copy[k] = v
 
     for state, char, files in changestates:
         if state in show:

mercurial/copies.py

@@ -109,6 +109,10 def copies(repo, c1, c2, ca, checkdirs=F
     if not c1 or not c2 or c1 == c2:
         return {}, {}
 
+    # avoid silly behavior for parent -> working dir
+    if c2.node() == None and c1.node() == repo.dirstate.parents()[0]:
+        return repo.dirstate.copies(), {}
+
     limit = _findlimit(repo, c1.rev(), c2.rev())
     m1 = c1.manifest()
     m2 = c2.manifest()

tests/test-merge-remove.out

@@ -13,7 +13,6 r 0 -1 foo1
 copy: foo -> foo1
 R bar
 R foo1
-  foo
 % readding foo1 and bar
 adding bar
 adding foo1