[PATCH 5 of 5 modernize-streamclone V2] streamclone: check for step completion

[Gregory Szorc]

# HG changeset patch
# User Gregory Szorc <gregory.szorc at gmail.com>
# Date 1443985736 25200
#      Sun Oct 04 12:08:56 2015 -0700
# Node ID 15c4dcd9b696c26292d86fedd3b44ef27fee10b9
# Parent  c90070c260be1174e33feff8743ca4b4f99af308
streamclone: check for step completion

The new behavior is consistent with all other pull steps. And it is the
correct behavior, as we never know what extensions may do.

diff --git a/mercurial/streamclone.py b/mercurial/streamclone.py
--- a/mercurial/streamclone.py
+++ b/mercurial/streamclone.py
@@ -28,8 +28,11 @@ def canperformstreamclone(pullop, bailif
     streaming clone is supported and False otherwise. ``requirements`` is
     a set of repo requirements from the remote, or ``None`` if stream clone
     isn't supported.
     """
+    if 'streamclone' in pullop.stepsdone:
+        return False, None
+
     repo = pullop.repo
     remote = pullop.remote
 
     bundle2supported = False