Merge branch 'bk/ancestry-path' into maint

* bk/ancestry-path:
t6019: avoid refname collision on case-insensitive systems
revision: do not include sibling history in --ancestry-path output
revision: keep track of the end-user input from the command line
rev-list: Demonstrate breakage with --ancestry-path --all

diff --cc revision.c
Simple merge

diff --cc revision.h
Simple merge