[PATCH STABLE] merge: avoid superfluous filemerges when grafting through renames (issue5407)

[Gábor Stefanik]

# HG changeset patch
# User Gábor Stefanik <gabor.stefanik at nng.com>
# Date 1477422113 -7200
#      Tue Oct 25 21:01:53 2016 +0200
# Branch stable
# Node ID 1f40c1fe34442812291b000c5e1a8b22ad14f091
# Parent  76c57e1fe79b0980b377b4f305635dea393d6315
merge: avoid superfluous filemerges when grafting through renames (issue5407)

This is a fix for a regression introduced by the patches for issue4028.

The test changes are due to us doing fewer _checkcopies searches now, which
makes some test outputs revert to the pre-issue4028 behavior. That issue itself
remains fixed, we only skip copy tracing for files where it isn't relevant.
As a nice side effect, this makes copy detection much faster when tracing
backwards through lots of renames.

diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -631,6 +631,10 @@
     backwards = not remotebase and base != tca and f in mb
     getfctx = _makegetfctx(ctx)
 
+    if m1[f] == mb.get(f) and not remotebase:
+        # Nothing to merge
+        return
+
     of = None
     seen = set([f])
     for oc in getfctx(f, m1[f]).ancestors():
diff --git a/tests/test-graft.t b/tests/test-graft.t
--- a/tests/test-graft.t
+++ b/tests/test-graft.t
@@ -181,9 +181,6 @@
     searching for copies back to rev 1
     unmatched files in other (from topological common ancestor):
      c
-    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
-     src: 'c' -> dst: 'b' *
-    checking for directory renames
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 4c60f11aa304, local: 6b9e5368ca4e+, remote: 97f8bfe72746
@@ -200,9 +197,6 @@
     searching for copies back to rev 1
     unmatched files in other (from topological common ancestor):
      c
-    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
-     src: 'c' -> dst: 'b' *
-    checking for directory renames
   resolving manifests
    branchmerge: True, force: True, partial: False
    ancestor: 4c60f11aa304, local: 1905859650ec+, remote: 9c233e8e184d
@@ -1280,3 +1274,15 @@
   
   $ hg cat f2c
   c2e
+
+Check superfluous filemerge of files renamed in the past but untouched by graft
+
+  $ echo a > a
+  $ hg ci -qAma
+  $ hg mv a b
+  $ echo b > b
+  $ hg ci -qAmb
+  $ echo c > c
+  $ hg ci -qAmc
+  $ hg up -q .~2
+  $ hg graft tip -qt:fail
diff --git a/tests/test-merge-local.t b/tests/test-merge-local.t
--- a/tests/test-merge-local.t
+++ b/tests/test-merge-local.t
@@ -66,7 +66,7 @@
   merging zzz1_merge_ok
   merging zzz2_merge_bad
   warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
-  2 files updated, 1 files merged, 2 files removed, 1 files unresolved
+  2 files updated, 1 files merged, 3 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges
   [1]
 
@@ -104,7 +104,7 @@
   merging zzz1_merge_ok
   merging zzz2_merge_bad
   warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
-  2 files updated, 1 files merged, 2 files removed, 1 files unresolved
+  2 files updated, 1 files merged, 3 files removed, 1 files unresolved
   use 'hg resolve' to retry unresolved file merges
   [1]
 
diff --git a/tests/test-up-local-change.t b/tests/test-up-local-change.t
--- a/tests/test-up-local-change.t
+++ b/tests/test-up-local-change.t
@@ -242,4 +242,11 @@
   -a
   +b
 
+test for superfluous filemerge of clean files renamed in the past
+
+  $ hg up -qC tip
+  $ echo c > c
+  $ hg add c
+  $ hg up -qt:fail 0
+
   $ cd ..