exchange: use command executor for getbundle

The code consuming the bundle has been moved to inside the
context manager, as that is supposed to be part of the API.
(Although it doesn't matter for version 1 peers.)

Differential Revision: https://phab.mercurial-scm.org/D3316

mercurial/exchange.py

@@ -1648,7 +1648,12 b' def _pullbundle2(pullop):'
             kwargs['obsmarkers'] = True
             pullop.stepsdone.add('obsmarkers')
     _pullbundle2extraprepare(pullop, kwargs)
-    bundle = pullop.remote.getbundle('pull', **pycompat.strkwargs(kwargs))
+
+    with pullop.remote.commandexecutor() as e:
+        args = dict(kwargs)
+        args['source'] = 'pull'
+        bundle = e.callcommand('getbundle', args).result()
+
     try:
         op = bundle2.bundleoperation(pullop.repo, pullop.gettransaction,
                                      source='pull')