next: remove duplicated targets when updating from an unstable changeset

--HG--
branch : stable
8 jobs for topic/stable/next-double in 6 minutes and 35 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #192386
checks-py2

00:01:48

passed #192387
checks-py3

00:01:32

passed #192392
doc

00:00:15

manual #192385
allowed to fail manual
pytype
passed #192388
tests-py2-cext

00:04:42

passed #192389
tests-py2-pure

00:06:26

passed #192390
tests-py3-cext

00:06:34

passed #192391
tests-py3-pure

00:03:07