diff -r f6b7617a85bb -r 3c20d7ef42e1 mercurial/localrepo.py
--- a/mercurial/localrepo.py	Tue Jul 11 03:47:25 2017 +0200
+++ b/mercurial/localrepo.py	Tue Jul 11 01:05:27 2017 +0200
@@ -1952,7 +1952,7 @@
                 # be compliant anyway
                 #
                 # if minimal phase was 0 we don't need to retract anything
-                phases.retractboundary(self, tr, targetphase, [n])
+                phases.registernew(self, tr, targetphase, [n])
             tr.close()
             return n
         finally: