streamclone: refactor maybeperformstreamclone to take a pullop

Just like all the other pull steps. Consistency is good.

This seems a little excessive right now since maybeperformstreamclone is
such a short function. This will be addressed in a subsequent patch.

mercurial/exchange.py

@@ -964,9 +964,7 b' def pull(repo, remote, heads=None, force'
     lock = pullop.repo.lock()
     try:
         pullop.trmanager = transactionmanager(repo, 'pull', remote.url())
-        streamclone.maybeperformstreamclone(pullop.repo, pullop.remote,
-                                            pullop.heads,
-                                            pullop.streamclonerequested)
+        streamclone.maybeperformstreamclone(pullop)
         _pulldiscovery(pullop)
         if _canusebundle2(pullop):
             _pullbundle2(pullop)

mercurial/streamclone.py

@@ -66,9 +66,14 b' def canperformstreamclone(repo, remote, '
 
     return True, requirements
 
-def maybeperformstreamclone(repo, remote, heads, stream):
-    supported, requirements = canperformstreamclone(repo, remote, heads,
-                                                     streamrequested=stream)
+def maybeperformstreamclone(pullop):
+    repo = pullop.repo
+    remote = pullop.remote
+
+    r = canperformstreamclone(repo, remote, pullop.heads,
+                              streamrequested=pullop.streamclonerequested)
+    supported, requirements = r
+
     if not supported:
         return