--- a/hgext3rd/evolve/__init__.py	Fri Jan 19 17:29:48 2018 +0530
+++ b/hgext3rd/evolve/__init__.py	Sun Jan 21 20:28:06 2018 +0530
@@ -947,54 +947,6 @@
     _deprecatealias('gup', 'next')
     _deprecatealias('gdown', 'previous')
 
-def _singlesuccessor(repo, p):
-    """returns p (as rev) if not obsolete or its unique latest successors
-
-    fail if there are no such successor"""
-
-    if not p.obsolete():
-        return p.rev()
-    obs = repo[p]
-    ui = repo.ui
-    newer = compat.successorssets(repo, obs.node())
-    # search of a parent which is not killed
-    while not newer:
-        ui.debug("stabilize target %s is plain dead,"
-                 " trying to stabilize on its parent\n" %
-                 obs)
-        obs = obs.parents()[0]
-        newer = compat.successorssets(repo, obs.node())
-    if len(newer) > 1 or len(newer[0]) > 1:
-        raise utility.MultipleSuccessorsError(newer)
-
-    return repo[newer[0][0]].rev()
-
-def builddependencies(repo, revs):
-    """returns dependency graphs giving an order to solve instability of revs
-    (see _orderrevs for more information on usage)"""
-
-    # For each troubled revision we keep track of what instability if any should
-    # be resolved in order to resolve it. Example:
-    # dependencies = {3: [6], 6:[]}
-    # Means that: 6 has no dependency, 3 depends on 6 to be solved
-    dependencies = {}
-    # rdependencies is the inverted dict of dependencies
-    rdependencies = collections.defaultdict(set)
-
-    for r in revs:
-        dependencies[r] = set()
-        for p in repo[r].parents():
-            try:
-                succ = _singlesuccessor(repo, p)
-            except utility.MultipleSuccessorsError as exc:
-                dependencies[r] = exc.successorssets
-                continue
-            if succ in revs:
-                dependencies[r].add(succ)
-                rdependencies[succ].add(r)
-    return dependencies, rdependencies
-
-
 def _orderrevs(repo, revs):
     """Compute an ordering to solve instability for the given revs
 
@@ -1008,7 +960,7 @@
     revision on its final stabilized destination.
     """
     # Step 1: Build the dependency graph
-    dependencies, rdependencies = builddependencies(repo, revs)
+    dependencies, rdependencies = utility.builddependencies(repo, revs)
     # 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
@@ -1153,7 +1105,7 @@
                                            {'template': shorttemplate})
         # no args and parent is obsolete, update to successors
         try:
-            ctx = repo[_singlesuccessor(repo, repo['.'])]
+            ctx = repo[utility._singlesuccessor(repo, repo['.'])]
         except utility.MultipleSuccessorsError as exc:
             repo.ui.write_err('parent is obsolete with multiple successors:\n')
             for ln in exc.successorssets:
@@ -1285,7 +1237,7 @@
 
     # we do not filter in the 1 case to allow prev to t0
     if currenttopic and topic and _gettopicidx(p1) != 1:
-        parents = [repo[_singlesuccessor(repo, ctx)] if ctx.mutable() else ctx
+        parents = [repo[utility._singlesuccessor(repo, ctx)] if ctx.mutable() else ctx
                    for ctx in parents]
         parents = [ctx for ctx in parents if ctx.topic() == currenttopic]
 

--- a/hgext3rd/evolve/utility.py	Fri Jan 19 17:29:48 2018 +0530
+++ b/hgext3rd/evolve/utility.py	Sun Jan 21 20:28:06 2018 +0530
@@ -5,8 +5,14 @@
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
+import collections
+
 from mercurial.node import nullrev
 
+from . import (
+    compat,
+)
+
 shorttemplate = "[{label('evolve.rev', rev)}] {desc|firstline}\n"
 
 def obsexcmsg(ui, message, important=False):
@@ -76,3 +82,50 @@
 
     def __init__(self, successorssets):
         self.successorssets = successorssets
+
+def builddependencies(repo, revs):
+    """returns dependency graphs giving an order to solve instability of revs
+    (see _orderrevs for more information on usage)"""
+
+    # For each troubled revision we keep track of what instability if any should
+    # be resolved in order to resolve it. Example:
+    # dependencies = {3: [6], 6:[]}
+    # Means that: 6 has no dependency, 3 depends on 6 to be solved
+    dependencies = {}
+    # rdependencies is the inverted dict of dependencies
+    rdependencies = collections.defaultdict(set)
+
+    for r in revs:
+        dependencies[r] = set()
+        for p in repo[r].parents():
+            try:
+                succ = _singlesuccessor(repo, p)
+            except MultipleSuccessorsError as exc:
+                dependencies[r] = exc.successorssets
+                continue
+            if succ in revs:
+                dependencies[r].add(succ)
+                rdependencies[succ].add(r)
+    return dependencies, rdependencies
+
+def _singlesuccessor(repo, p):
+    """returns p (as rev) if not obsolete or its unique latest successors
+
+    fail if there are no such successor"""
+
+    if not p.obsolete():
+        return p.rev()
+    obs = repo[p]
+    ui = repo.ui
+    newer = compat.successorssets(repo, obs.node())
+    # search of a parent which is not killed
+    while not newer:
+        ui.debug("stabilize target %s is plain dead,"
+                 " trying to stabilize on its parent\n" %
+                 obs)
+        obs = obs.parents()[0]
+        newer = compat.successorssets(repo, obs.node())
+    if len(newer) > 1 or len(newer[0]) > 1:
+        raise MultipleSuccessorsError(newer)
+
+    return repo[newer[0][0]].rev()