# HG changeset patch
# User Pulkit Goyal <7895pulkit@gmail.com>
# Date 1498010531 -19800
# Node ID cf930521f14db1e9e926acdbd95709f7fc40f569
# Parent  d8b47d961c7778c1987fea94d545ddc55fad83f5
topics: add some noise to rewrittent changeset to prevent hash cycle

If we have a changeset with topic `x`, we change it's topic to `y`, fine.
When we change it's topic back again to `x`, we get the hash of the the
obsoleted changeset which had the topic `x` initially. The same happens for few
more cases like clearing the topic of a changeset which initially had no topic.

This approach is influenced from cmdutil.amend and other commands (rebase, histedit, etc…)

diff -r d8b47d961c77 -r cf930521f14d hgext3rd/topic/__init__.py
--- a/hgext3rd/topic/__init__.py	Wed Jun 21 13:18:47 2017 +0200
+++ b/hgext3rd/topic/__init__.py	Wed Jun 21 07:32:11 2017 +0530
@@ -331,6 +331,7 @@
                 del fixedextra[constants.extrakey]
             else:
                 fixedextra[constants.extrakey] = newtopic
+            fixedextra[constants.changekey] = c.hex()
             if 'amend_source' in fixedextra:
                 # TODO: right now the commitctx wrapper in
                 # topicrepo overwrites the topic in extra if
diff -r d8b47d961c77 -r cf930521f14d hgext3rd/topic/constants.py
--- a/hgext3rd/topic/constants.py	Wed Jun 21 13:18:47 2017 +0200
+++ b/hgext3rd/topic/constants.py	Wed Jun 21 07:32:11 2017 +0530
@@ -1,1 +1,2 @@
 extrakey = 'topic'
+changekey = '_rewrite_noise'
diff -r d8b47d961c77 -r cf930521f14d tests/test-topic.t
--- a/tests/test-topic.t	Wed Jun 21 13:18:47 2017 +0200
+++ b/tests/test-topic.t	Wed Jun 21 07:32:11 2017 +0530
@@ -556,7 +556,7 @@
   changed topic on 1 changes
   please run hg evolve --rev "not topic()" now
   $ hg log -Gr 'draft() and not obsolete()'
-  o  changeset:   11:783930e1d79e
+  o  changeset:   11:0beca5ab56c3
   |  tag:         tip
   |  parent:      3:a53952faf762
   |  user:        test
@@ -581,7 +581,7 @@
   changed topic on 1 changes
   please run hg evolve --rev "topic(wat)" now
   $ hg log -Gr 'draft() and not obsolete()'
-  o  changeset:   13:d91cd8fd490e
+  o  changeset:   13:686a642006db
   |  tag:         tip
   |  topic:       wat
   |  parent:      3:a53952faf762
@@ -589,7 +589,7 @@
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     start on fran
   |
-  | @  changeset:   12:d9e32f4c4806
+  | @  changeset:   12:18b70b8de1f0
   | |  user:        test
   | |  date:        Thu Jan 01 00:00:00 1970 +0000
   | |  trouble:     unstable
@@ -600,17 +600,17 @@
 bonus deps in the testsuite.
 
   $ hg rebase -d tip -s .
-  rebasing 12:d9e32f4c4806 "fran?"
+  rebasing 12:18b70b8de1f0 "fran?"
 
   $ hg log -Gr 'draft()'
-  @  changeset:   14:cf24ad8bbef5
+  @  changeset:   14:503497a14c3e
   |  tag:         tip
   |  topic:       wat
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     fran?
   |
-  o  changeset:   13:d91cd8fd490e
+  o  changeset:   13:686a642006db
   |  topic:       wat
   |  parent:      3:a53952faf762
   |  user:        test
@@ -623,15 +623,15 @@
   $ hg topic watwat
   $ hg ci --amend
   $ hg log -Gr 'draft()'
-  @  changeset:   16:893ffcf66c1f
+  @  changeset:   16:024d9c69f30f
   |  tag:         tip
   |  topic:       watwat
-  |  parent:      13:d91cd8fd490e
+  |  parent:      13:686a642006db
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     fran?
   |
-  o  changeset:   13:d91cd8fd490e
+  o  changeset:   13:686a642006db
   |  topic:       wat
   |  parent:      3:a53952faf762
   |  user:        test
@@ -644,9 +644,9 @@
   $ hg topic --clear
   $ hg ci --amend
   $ hg log -r .
-  changeset:   18:a13639e22b65
+  changeset:   18:573ab57c6de2
   tag:         tip
-  parent:      13:d91cd8fd490e
+  parent:      13:686a642006db
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     fran?
@@ -661,15 +661,15 @@
   $ hg co 19
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg log -Gr 'draft()'
-  @  changeset:   19:b72b86a1f96b
+  @  changeset:   19:2539ecb09b37
   |  tag:         tip
   |  topic:       watwat
-  |  parent:      13:d91cd8fd490e
+  |  parent:      13:686a642006db
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     fran?
   |
-  o  changeset:   13:d91cd8fd490e
+  o  changeset:   13:686a642006db
   |  topic:       wat
   |  parent:      3:a53952faf762
   |  user:        test
@@ -683,14 +683,14 @@
   changed topic on 2 changes
   please run hg evolve --rev "topic(changewat)" now
   $ hg log -Gr 'draft()'
-  @  changeset:   21:58e15a6365ca
+  @  changeset:   21:993d145391f5
   |  tag:         tip
   |  topic:       changewat
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     fran?
   |
-  o  changeset:   20:a96ac830b62e
+  o  changeset:   20:ceba5be9d56f
   |  topic:       changewat
   |  parent:      3:a53952faf762
   |  user:        test
@@ -707,21 +707,21 @@
   $ echo gamma >> gamma
   $ hg ci -m gamma
   $ hg log -Gr 'draft()'
-  @  changeset:   22:373f490f8854
+  @  changeset:   22:0d3d805542b4
   |  tag:         tip
   |  topic:       changewat
-  |  parent:      20:a96ac830b62e
+  |  parent:      20:ceba5be9d56f
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     gamma
   |
-  | o  changeset:   21:58e15a6365ca
+  | o  changeset:   21:993d145391f5
   |/   topic:       changewat
   |    user:        test
   |    date:        Thu Jan 01 00:00:00 1970 +0000
   |    summary:     fran?
   |
-  o  changeset:   20:a96ac830b62e
+  o  changeset:   20:ceba5be9d56f
   |  topic:       changewat
   |  parent:      3:a53952faf762
   |  user:        test
@@ -734,21 +734,21 @@
   changed topic on 3 changes
   please run hg evolve --rev "topic(changewut)" now
   $ hg log -Gr 'draft()'
-  @  changeset:   25:05d1bf93e1d8
+  @  changeset:   25:729ed5717393
   |  tag:         tip
   |  topic:       changewut
-  |  parent:      23:1f668635e0c2
+  |  parent:      23:62e49f09f883
   |  user:        test
   |  date:        Thu Jan 01 00:00:00 1970 +0000
   |  summary:     gamma
   |
-  | o  changeset:   24:696f1024fbfb
+  | o  changeset:   24:658ae31a0c05
   |/   topic:       changewut
   |    user:        test
   |    date:        Thu Jan 01 00:00:00 1970 +0000
   |    summary:     fran?
   |
-  o  changeset:   23:1f668635e0c2
+  o  changeset:   23:62e49f09f883
   |  topic:       changewut
   |  parent:      3:a53952faf762
   |  user:        test