[PATCH] adjustlinkrev: search ancestors from oldest to newest

[Martin von Zweigbergk]

# HG changeset patch
# User Martin von Zweigbergk <martinvonz at google.com>
# Date 1421273570 28800
#      Wed Jan 14 14:12:50 2015 -0800
# Node ID 5b82ace74f36afe0ec6d44d17489b844724cd708
# Parent  b2358bc1407c19007b0e7852262f61d5fe7a8f83
adjustlinkrev: search ancestors from oldest to newest

When searching for the oldest ancestor that introduced a file's node
id, we search in the order we get from changelog.ancestors(), which is
in descending order (newest to oldest). For file modifications, it is
safe to search backwards like this, but for when the file has been
temporarily removed, the same nodeid can appear twice. Make sure we
search from oldest to newest so we get the right result in this case
too.

diff -r b2358bc1407c -r 5b82ace74f36 mercurial/context.py
--- a/mercurial/context.py	Tue Jan 13 15:08:55 2015 -0500
+++ b/mercurial/context.py	Wed Jan 14 14:12:50 2015 -0800
@@ -23,7 +23,7 @@
 _newnode = '!' * 21
 
 def _adjustlinkrev(repo, path, filelog, fnode, srcrev, inclusive=False):
-    """return the first ancestor of <srcrev> introducting <fnode>
+    """return the oldest ancestor of <srcrev> introducting <fnode>
 
     If the linkrev of the file revision does not point to an ancestor of
     srcrev, we'll walk down the ancestors until we find one introducing this
@@ -42,7 +42,8 @@
     fr = filelog.rev(fnode)
     lkr = filelog.linkrev(fr)
     # check if this linkrev is an ancestor of srcrev
-    anc = cl.ancestors([srcrev], lkr, inclusive=inclusive)
+    anc = list(cl.ancestors([srcrev], lkr, inclusive=inclusive))
+    anc.reverse()
     if lkr not in anc:
         for a in anc:
             ac = cl.read(a) # get changeset data (we avoid object creation).
diff -r b2358bc1407c -r 5b82ace74f36 tests/test-log.t
--- a/tests/test-log.t	Tue Jan 13 15:08:55 2015 -0500
+++ b/tests/test-log.t	Wed Jan 14 14:12:50 2015 -0800
@@ -1842,3 +1842,21 @@
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     1
   |
+
+  $ hg up -q 3
+  $ hg ci --amend -m 'new message'
+  $ hg rm b
+  $ hg ci -m 'remove b'
+  $ hg revert -r 5 b
+  $ hg ci -m 'recover b'
+
+The same filerev now exists in hidden rev 3, as well as in visible rev 5 and 7,
+so 5 is the first visible and should be displayed.
+
+  $ hg log b
+  changeset:   5:71488aa303fd
+  parent:      0:f7b1eb17ad24
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  summary:     new message
+