Merge branch 'jk/reflog-walk' into maint

Numerous bugs in walking of reflogs via "log -g" and friends have
been fixed.

* jk/reflog-walk:
reflog-walk: apply --since/--until to reflog dates
reflog-walk: stop using fake parents
rev-list: check reflog_info before showing usage
get_revision_1(): replace do-while with an early return
log: do not free parents when walking reflog
log: clarify comment about reflog cycles
revision: disallow reflog walking with revs->limited
t1414: document some reflog-walk oddities

diff --cc builtin/log.c
Simple merge

diff --cc builtin/rev-list.c
Simple merge

diff --cc revision.c
Simple merge