changegroup: wrap some ** expansions in strkwargs

mercurial/changegroup.py

@@ -266,7 +266,8 b' class cg1unpacker(object):'
             # in this function.
             srctype = tr.hookargs.setdefault('source', srctype)
             url = tr.hookargs.setdefault('url', url)
-            repo.hook('prechangegroup', throw=True, **tr.hookargs)
+            repo.hook('prechangegroup',
+                      throw=True, **pycompat.strkwargs(tr.hookargs))
 
             # write changelog data to temp files so concurrent readers
             # will not see an inconsistent view
@@ -353,7 +354,8 b' class cg1unpacker(object):'
                     hookargs = dict(tr.hookargs)
                     hookargs['node'] = hex(cl.node(clstart))
                     hookargs['node_last'] = hex(cl.node(clend - 1))
-                repo.hook('pretxnchangegroup', throw=True, **hookargs)
+                repo.hook('pretxnchangegroup',
+                          throw=True, **pycompat.strkwargs(hookargs))
 
             added = [cl.node(r) for r in xrange(clstart, clend)]
             phaseall = None