hg merge: fix time asymmetry bug with deleting files on update to past

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hg merge: fix time asymmetry bug with deleting files on update to past

manifest hash: 41feb7bf9b56e071a538a0918224898acb2bd31c
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tests/test-backwards-remove

@@ -0,0 +1,12 b''
+#!/bin/sh -x
+hg init
+echo This is file a1 > a
+hg add a
+hg commit -t "commit #0" -d "0 0" -u user
+ls
+echo This is file b1 > b
+hg add b
+hg commit -t "commit #1" -d "0 0" -u user
+hg co 0
+# B should disappear
+ls

tests/test-backwards-remove.out

@@ -0,0 +1,12 b''
++ hg init
++ echo This is file a1
++ hg add a
++ hg commit -t 'commit #0' -d '0 0' -u user
++ ls
+a
++ echo This is file b1
++ hg add b
++ hg commit -t 'commit #1' -d '0 0' -u user
++ hg co 0
++ ls
+a

mercurial/hg.py

@@ -1076,7 +1076,11 b' class localrepository:'
                     remove.append(f) # other deleted it
             else:
                 if n == m1.get(f, nullid): # same as parent
-                    self.ui.debug("local created %s, keeping\n" % f)
+                    if p2 == pa: # going backwards?
+                        self.ui.debug("remote deleted %s\n" % f)
+                        remove.append(f)
+                    else:
+                        self.ui.debug("local created %s, keeping\n" % f)
                 else:
                     self.ui.debug("working dir created %s, keeping\n" % f)