--- a/hgext3rd/evolve/obsdiscovery.py
+++ b/hgext3rd/evolve/obsdiscovery.py
@@ -273,7 +273,7 @@
     rangelength = repo.stablerange.rangelength
     depthrev = repo.stablerange.depthrev
     if opts['subranges']:
-        ranges = stablerange.subrangesclosure(repo, revs)
+        ranges = stablerange.subrangesclosure(repo, repo.stablerange, revs)
     else:
         ranges = [(r, 0) for r in revs]
     headers = ('rev', 'node', 'index', 'size', 'depth', 'obshash')

--- a/hgext3rd/evolve/stablerange.py
+++ b/hgext3rd/evolve/stablerange.py
@@ -52,12 +52,12 @@
     """return highest power of two lower than 'i'"""
     return 2 ** int(math.log(i - 1, 2))
 
-def subrangesclosure(repo, heads):
+def subrangesclosure(repo, stablerange, heads):
     """set of all standard subrange under heads
 
     This is intended for debug purposes. Range are returned from largest to
     smallest in terms of number of revision it contains."""
-    subranges = repo.stablerange.subranges
+    subranges = stablerange.subranges
     toproceed = [(r, 0, ) for r in heads]
     ranges = set(toproceed)
     while toproceed:
@@ -68,16 +68,22 @@
                 toproceed.append(r)
     ranges = list(ranges)
     n = repo.changelog.node
-    rangelength = repo.stablerange.rangelength
+    rangelength = stablerange.rangelength
     ranges.sort(key=lambda r: (-rangelength(repo, r), n(r[0])))
     return ranges
 
+_stablerangemethodmap = {
+    'branchpoint': lambda repo: repo.stablerange,
+}
+
 @eh.command(
     'debugstablerange',
     [
-        ('', 'rev', [], 'operate on (rev, 0) ranges for rev in REVS'),
+        ('r', 'rev', [], 'operate on (rev, 0) ranges for rev in REVS'),
         ('', 'subranges', False, 'recursively display data for subranges too'),
         ('', 'verify', False, 'checks subranges content (EXPENSIVE)'),
+        ('', 'method', 'branchpoint',
+         'method to use, one of "branchpoint", "mergepoint"')
     ],
     _(''))
 def debugstablerange(ui, repo, **opts):
@@ -88,20 +94,8 @@
     """
     short = nodemod.short
     revs = scmutil.revrange(repo, opts['rev'])
-    # prewarm depth cache
-    unfi = repo.unfiltered()
-    node = unfi.changelog.node
-    stablerange = unfi.stablerange
-    depth = stablerange.depthrev
-    length = stablerange.rangelength
-    subranges = stablerange.subranges
     if not revs:
         raise error.Abort('no revisions specified')
-    repo.stablerange.warmup(repo, max(revs))
-    if opts['subranges']:
-        ranges = subrangesclosure(repo, revs)
-    else:
-        ranges = [(r, 0) for r in revs]
     if ui.verbose:
         template = '%s-%d (%d, %d, %d)'
 
@@ -121,6 +115,25 @@
                 short(node(rangeid[0])),
                 rangeid[1],
             )
+    # prewarm depth cache
+    unfi = repo.unfiltered()
+    node = unfi.changelog.node
+
+    method = opts['method']
+    getstablerange = _stablerangemethodmap.get(method)
+    if getstablerange is None:
+        raise error.Abort('unknown stable sort method: "%s"' % method)
+
+    stablerange = getstablerange(unfi)
+    depth = stablerange.depthrev
+    length = stablerange.rangelength
+    subranges = stablerange.subranges
+    stablerange.warmup(repo, max(revs))
+
+    if opts['subranges']:
+        ranges = subrangesclosure(repo, stablerange, revs)
+    else:
+        ranges = [(r, 0) for r in revs]
 
     for r in ranges:
         subs = subranges(unfi, r)