bundle2: use an official iterparts method to unbundle parts

Explicit is better than implicit.

mercurial/bundle2.py

@@ -286,7 +286,7 b' def processbundle(repo, unbundler, trans'
     # - replace this is a init function soon.
     # - exception catching
     unbundler.params
-    iterparts = iter(unbundler)
+    iterparts = unbundler.iterparts()
     part = None
     try:
         for part in iterparts:
@@ -397,7 +397,8 b' class unpackermixin(object):'
 class unbundle20(unpackermixin):
     """interpret a bundle2 stream
 
-    (this will eventually yield parts)"""
+    This class is fed with a binary stream and yields parts through its
+    `iterparts` methods."""
 
     def __init__(self, ui, fp, header=None):
         """If header is specified, we do not read it out of the stream."""
@@ -450,7 +451,7 b' class unbundle20(unpackermixin):'
             raise KeyError(name)
 
 
-    def __iter__(self):
+    def iterparts(self):
         """yield all parts contained in the stream"""
         # make sure param have been loaded
         self.params

tests/test-bundle2.t

@@ -143,7 +143,7 b' Create an extension to test bundle2 API'
   >         if value is not None:
   >             ui.write('    %s\n' % value)
   >     count = 0
-  >     for p in unbundler:
+  >     for p in unbundler.iterparts():
   >         count += 1
   >         ui.write('  :%s:\n' % p.type)
   >         ui.write('    mandatory: %i\n' % len(p.mandatoryparams))