13 import weakref

    13 import weakref

    14 

    14 

    15 from .i18n import _

    15 from .i18n import _

    16 from .node import (

    16 from .node import (

    17     hex,

    17     hex,

    19     nullrev,

    18     nullrev,

    20     short,

    19     short,

    21 )

    20 )

    22 from .pycompat import open

    21 from .pycompat import open

    23 

    22 

   671     # revisions, we need to invent a header that says to rewrite

   670     # revisions, we need to invent a header that says to rewrite

   672     # data.

   671     # data.

   673 

   672 

   674     if delta.delta is not None:

   673     if delta.delta is not None:

   675         prefix, data = b'', delta.delta

   674         prefix, data = b'', delta.delta

   677         data = delta.revision

   676         data = delta.revision

   678         prefix = mdiff.trivialdiffheader(len(data))

   677         prefix = mdiff.trivialdiffheader(len(data))

   679     else:

   678     else:

   680         data = delta.revision

   679         data = delta.revision

   681         prefix = mdiff.replacediffheader(delta.baserevisionsize, len(data))

   680         prefix = mdiff.replacediffheader(delta.baserevisionsize, len(data))