--- a/hgext3rd/evolve/obshistory.py	Fri May 19 19:52:57 2017 +0200
+++ b/hgext3rd/evolve/obshistory.py	Fri May 19 20:15:05 2017 +0200
@@ -361,6 +361,7 @@
 DESCCHANGED = 1 << 0 # action changed the description
 METACHANGED = 1 << 1 # action change the meta (user, date, branch, etc...)
 PARENTCHANGED = 1 << 2 # action change the parent
+DIFFCHANGED = 1 << 3 # action change diff introduced by the changeset
 
 def geteffectflag(relation):
     """compute the effect flag by comparing the source and destination"""
@@ -387,8 +388,34 @@
         if changectx.parents() != source.parents():
             effects |= PARENTCHANGED
 
+        if not _cmpdiff(source, changectx):
+            effects |= DIFFCHANGED
+
     return effects
 
+def _getdiffline(iterdiff):
+    """return a cleaned up line"""
+    try:
+        line = iterdiff.next()
+    except StopIteration:
+        return None
+    return line
+
+def _cmpdiff(leftctx, rightctx):
+    """return True if both ctx introduce the "same diff"
+
+    This is a first and basic implementation, with many shortcoming.
+    """
+    leftdiff = leftctx.diff(git=1)
+    rightdiff = rightctx.diff(git=1)
+    left, right = (0, 0)
+    while None not in (left, right):
+        left = _getdiffline(leftdiff)
+        right = _getdiffline(rightdiff)
+        if left != right:
+            return False
+    return True
+
 @eh.wrapfunction(obsolete, 'createmarkers')
 def createmarkerswithbits(orig, repo, relations, flag=0, date=None, metadata=None):
     """compute 'effect-flag' and augment the created markers

--- a/tests/test-evolve-effectflags.t	Fri May 19 19:52:57 2017 +0200
+++ b/tests/test-evolve-effectflags.t	Fri May 19 20:15:05 2017 +0200
@@ -71,3 +71,22 @@
   x  2ee0a31bd600 (6) D0
        rewritten by test (*) as 131ac3eecd92 (glob)
   
+
+amend touching the diff
+-----------------------
+
+  $ mkcommit E0
+  $ echo 42 >> E0
+  $ hg amend
+
+check result
+
+  $ hg debugobsolete --rev .
+  5734caf1004261ffc2ed05763b82bf9d75ba3788 0 {f75604747b4fd2dfebe7f48c6e629aea15e3b237} (*) {'ef1': '0', 'user': 'test'} (glob)
+  f75604747b4fd2dfebe7f48c6e629aea15e3b237 bed7e49faeb8ae06649b547a755d50f5bb0be220 0 (*) {'ef1': '8', 'user': 'test'} (glob)
+  $ hg obslog .
+  @  bed7e49faeb8 (10) E0
+  |
+  x  f75604747b4f (8) E0
+       rewritten by test (*) as bed7e49faeb8 (glob)
+