--- a/README	Wed Sep 27 16:24:44 2017 +0200
+++ b/README	Sat Sep 30 11:11:04 2017 +0100
@@ -121,6 +121,11 @@
 Changelog
 =========
 
+6.7.1 - in progress
+-------------------
+
+  * stack: fix evolution previous for simple split
+
 6.7.0 -- 2017-09-27
 -------------------
 

--- a/hgext3rd/topic/evolvebits.py	Wed Sep 27 16:24:44 2017 +0200
+++ b/hgext3rd/topic/evolvebits.py	Sat Sep 30 11:11:04 2017 +0100
@@ -81,8 +81,16 @@
                  obs)
         obs = obs.parents()[0]
         newer = compat.successorssets(repo, obs.node())
-    if len(newer) > 1 or len(newer[0]) > 1:
+    if 1 < len(newer):
+        # divergence case
+        # we should pick as arbitrary one
         raise MultipleSuccessorsError(newer)
+    elif 1 < len(newer[0]):
+        splitheads = list(repo.revs('heads(%ln::%ln)', newer[0], newer[0]))
+        if 1 < len(splitheads):
+            # split case, See if we can make sense of it.
+            raise MultipleSuccessorsError(newer)
+        return splitheads[0]
 
     return repo[newer[0][0]].rev()
 

--- a/tests/test-topic-stack.t	Wed Sep 27 16:24:44 2017 +0200
+++ b/tests/test-topic-stack.t	Sat Sep 30 11:11:04 2017 +0100
@@ -7,7 +7,7 @@
   > [ui]
   > logtemplate = {rev} {branch} \{{get(namespaces, "topics")}} {phase} {desc|firstline}\n
   > [experimental]
-  > evolution=createmarkers,exchange,allowunstable
+  > evolution=all
   > EOF
 
   $ hg init main
@@ -791,3 +791,125 @@
     ^ c_F
   t1$ c_D (current unstable)
   t0^ c_C (base)
+
+Test stack behavior with a split
+--------------------------------
+
+get things linear again
+
+  $ hg rebase -r t1 -d default
+  rebasing 16:1d84ec948370 "c_D" (tip)
+  switching to topic blue
+  $ hg rebase -r t2 -d t1
+  rebasing 13:3ab2eedae500 "c_G"
+  $ hg rebase -r t3 -d t2
+  rebasing 8:3bfe800e0486 "c_I"
+  $ hg stack
+  ### topic: blue
+  ### target: default (branch)
+  t3: c_I
+  t2: c_G
+  t1@ c_D (current)
+  t0^ c_A (base)
+
+making a split
+(first get something to split)
+
+  $ hg up t2
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ hg status --change .
+  A ggg
+  $ echo zzz > Z
+  $ hg add Z
+  $ hg commit --amend
+  $ hg status --change .
+  A Z
+  A ggg
+  $ hg stack
+  ### topic: blue
+  ### target: default (branch)
+  t3$ c_I (unstable)
+  t2@ c_G (current)
+  t1: c_D
+  t0^ c_A (base)
+  $ hg --config extensions.evolve=  --config ui.interactive=yes split << EOF
+  > y
+  > y
+  > n
+  > y
+  > EOF
+  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
+  adding Z
+  adding ggg
+  diff --git a/Z b/Z
+  new file mode 100644
+  examine changes to 'Z'? [Ynesfdaq?] y
+  
+  @@ -0,0 +1,1 @@
+  +zzz
+  record change 1/2 to 'Z'? [Ynesfdaq?] y
+  
+  diff --git a/ggg b/ggg
+  new file mode 100644
+  examine changes to 'ggg'? [Ynesfdaq?] n
+  
+  Done splitting? [yN] y
+
+  $ hg --config extensions.evolve= obslog --all
+  o  dde94df880e9 (22) c_G
+  |
+  | @  e7ea874afbd5 (23) c_G
+  |/
+  x  b24bab30ac12 (21) c_G
+  |    rewritten(parent, content) as dde94df880e9, e7ea874afbd5 by test (Thu Jan 01 00:00:00 1970 +0000)
+  |
+  x  907f7d3c2333 (18) c_G
+  |    rewritten as b24bab30ac12 by test (Thu Jan 01 00:00:00 1970 +0000)
+  |
+  x  3ab2eedae500 (13) c_G
+  |    rewritten as 907f7d3c2333 by test (Thu Jan 01 00:00:00 1970 +0000)
+  |
+  x  c7d60a180d05 (6) c_G
+       rewritten as 3ab2eedae500 by test (Thu Jan 01 00:00:00 1970 +0000)
+  
+  $ hg export .
+  # HG changeset patch
+  # User test3
+  # Date 0 0
+  #      Thu Jan 01 00:00:00 1970 +0000
+  # Node ID e7ea874afbd5c17aeee366d39a828dbcb01682ce
+  # Parent  dde94df880e97f4a1ee8c5408254b429b3d90204
+  # EXP-Topic blue
+  c_G
+  
+  diff -r dde94df880e9 -r e7ea874afbd5 ggg
+  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/ggg	Thu Jan 01 00:00:00 1970 +0000
+  @@ -0,0 +1,1 @@
+  +ggg
+  $ hg export .^
+  # HG changeset patch
+  # User test3
+  # Date 0 0
+  #      Thu Jan 01 00:00:00 1970 +0000
+  # Node ID dde94df880e97f4a1ee8c5408254b429b3d90204
+  # Parent  f3328cd199dc389b850ca952f65a15a8e6dbc79b
+  # EXP-Topic blue
+  c_G
+  
+  diff -r f3328cd199dc -r dde94df880e9 Z
+  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+  +++ b/Z	Thu Jan 01 00:00:00 1970 +0000
+  @@ -0,0 +1,1 @@
+  +zzz
+
+Check that stack ouput still make sense
+
+  $ hg stack
+  ### topic: blue
+  ### target: default (branch)
+  t4$ c_I (unstable)
+  t3@ c_G (current)
+  t2: c_G
+  t1: c_D
+  t0^ c_A (base)