539                     b'invalid successors nullid'

   539                     b'invalid successors nullid'

   540                 )

   540                 )

   541             )

   541             )

   542 

   542 

   543 

   543 

   545     """Store obsolete markers

   545     """Store obsolete markers

   546 

   546 

   547     Markers can be accessed with two mappings:

   547     Markers can be accessed with two mappings:

   548     - predecessors[x] -> set(markers on predecessors edges of x)

   548     - predecessors[x] -> set(markers on predecessors edges of x)

   549     - successors[x] -> set(markers on successors edges of x)

   549     - successors[x] -> set(markers on successors edges of x)