diff -r 54af8de9bd09 -r 57980af73cfa mercurial/obsutil.py
--- a/mercurial/obsutil.py	Thu Jul 06 14:54:22 2017 +0200
+++ b/mercurial/obsutil.py	Thu Jul 06 14:55:12 2017 +0200
@@ -311,6 +311,7 @@
 DESCCHANGED = 1 << 0 # action changed the description
 USERCHANGED = 1 << 4 # the user changed
 DATECHANGED = 1 << 5 # the date changed
+BRANCHCHANGED = 1 << 6 # the branch changed
 
 def geteffectflag(relation):
     """ From an obs-marker relation, compute what changed between the
@@ -333,6 +334,10 @@
         if changectx.date() != source.date():
             effects |= DATECHANGED
 
+        # Check if branch has changed
+        if changectx.branch() != source.branch():
+            effects |= BRANCHCHANGED
+
     return effects
 
 def getobsoleted(repo, tr):