+ +ends list of ends E(C,Px+)
+ format is one line per Px for which E(C,Px+) != { }
+ the line contains the patch name Px plus
+ the commit object names for E(C,Px+),
+ separated by spaces
+ in the case of tip commits, the commit's patch
+ is not listed; for these implicitly E(C,Px+) = { C }
+ always exists in tip and base branches, perhaps as
+ an empty file
+