--- a/CHANGELOG	Sun Sep 08 21:24:45 2019 +0200
+++ b/CHANGELOG	Tue Sep 10 07:38:46 2019 +0200
@@ -14,7 +14,10 @@
 9.1.1 - in progress
 -------------------
 
+  * evolve: test that target is not orig in _solveunstable() (issue6097)
+  * fold: check allowdivergence before folding obsolete changesets (issue5817)
   * obslog: correct spacing of patch output with word-diff=yes (issue6175)
+  * stack: make sure to preserve dependencies, fixes certain complex cases
 
 9.1.0 -- 2019-07-29
 -------------------

--- a/hgext3rd/evolve/cmdrewrite.py	Sun Sep 08 21:24:45 2019 +0200
+++ b/hgext3rd/evolve/cmdrewrite.py	Tue Sep 10 07:38:46 2019 +0200
@@ -762,6 +762,14 @@
         ui.write_err(_(b'single revision specified, nothing to fold\n'))
         return 1
 
+    if not ui.configbool(b'experimental', b'evolution.allowdivergence'):
+        for rev in revs:
+            if repo[rev].obsolete():
+                msg = _(b'folding obsolete revisions may cause divergence')
+                hint = _(b'set experimental.evolution.allowdivergence=yes'
+                         b' to allow folding them')
+                raise error.Abort(msg, hint=hint)
+
     # Sort so combined commit message of `hg fold --exact -r . -r .^` is
     # in topological order.
     revs.sort()

--- a/hgext3rd/topic/stack.py	Sun Sep 08 21:24:45 2019 +0200
+++ b/hgext3rd/topic/stack.py	Tue Sep 10 07:38:46 2019 +0200
@@ -143,9 +143,18 @@
         # processed dependency graph.
 
         # Step 1: compute relation of revision with each other
-        dependencies, rdependencies = self._dependencies
-        dependencies = dependencies.copy()
-        rdependencies = rdependencies.copy()
+        origdeps, rdependencies = self._dependencies
+        dependencies = {}
+        # Making a deep copy of origdeps because we modify contents of values
+        # later on. Checking for list here only because right now
+        # builddependencies in evolvebits.py can return a list of _succs()
+        # objects. When that will be dealt with, this deep copy code can be
+        # simplified a lot.
+        for k, v in origdeps.items():
+            if isinstance(v, list):
+                dependencies[k] = [i.copy() for i in v]
+            else:
+                dependencies[k] = v.copy()
         # Step 2: Build the ordering
         # Remove the revisions with no dependency(A) and add them to the ordering.
         # Removing these revisions leads to new revisions with no dependency (the

--- a/tests/test-fold.t	Sun Sep 08 21:24:45 2019 +0200
+++ b/tests/test-fold.t	Tue Sep 10 07:38:46 2019 +0200
@@ -254,7 +254,8 @@
   
 Test order of proposed commit message
 
-  $ hg fold --exact --hidden -r 4 -r 5 -r 6
+  $ hg fold --exact --hidden -r 4 -r 5 -r 6 \
+  >         --config experimental.evolution.allowdivergence=yes
   2 new content-divergent changesets
   3 changesets folded
   $ hg log -r tip -T '{desc}'
@@ -265,7 +266,8 @@
   
   
   r6 (no-eol)
-  $ hg fold --exact --hidden -r 6 -r 4 -r 5
+  $ hg fold --exact --hidden -r 6 -r 4 -r 5 \
+  >         --config experimental.evolution.allowdivergence=yes
   3 changesets folded
   $ hg log -r tip -T '{desc}'
   r4
@@ -381,3 +383,37 @@
   o  0: r0
   
   $ cd ..
+
+Fold should respect experimental.evolution.allowdivergence option
+https://bz.mercurial-scm.org/show_bug.cgi?id=5817
+
+  $ hg init issue5817
+  $ cd issue5817
+
+  $ echo A > foo
+  $ hg ci -qAm A
+  $ echo B > foo
+  $ hg ci -m B
+  $ echo C > foo
+  $ hg ci -m C
+
+  $ hg fold --exact -r 'desc("A")::desc("B")' -m 'first fold'
+  1 new orphan changesets
+  2 changesets folded
+
+fold aborts here because divergence is not allowed
+
+  $ hg fold --exact -r 'desc("A")::desc("B")' -m 'second fold' \
+  >         --config experimental.evolution.allowdivergence=no
+  abort: folding obsolete revisions may cause divergence
+  (set experimental.evolution.allowdivergence=yes to allow folding them)
+  [255]
+
+but if we allow divergence, this should work and should create new content-divergent changesets
+
+  $ hg fold --exact -r 'desc("A")::desc("B")' -m 'second fold' \
+  >         --config experimental.evolution.allowdivergence=yes
+  2 new content-divergent changesets
+  2 changesets folded
+
+  $ cd ..

--- a/tests/test-topic-stack.t	Sun Sep 08 21:24:45 2019 +0200
+++ b/tests/test-topic-stack.t	Tue Sep 10 07:38:46 2019 +0200
@@ -794,7 +794,7 @@
 
   $ hg stack red
   ### topic: red
-  ### target: default (branch), ambiguous rebase destination - topic 'red' has 3 heads
+  ### target: default (branch), 7 behind
   s5$ c_H (orphan)
     ^ c_G
     ^ c_D
@@ -868,7 +868,7 @@
 
   $ hg stack red
   ### topic: red
-  ### target: default (branch), ambiguous rebase destination - topic 'red' has 3 heads
+  ### target: default (branch), 7 behind
   s5$ c_H (orphan)
     ^ c_G
     ^ c_D