Added --branch-log to option to fast-import.
Added --branch-log to option to fast-import.

This option can be used to have a record of every commit, the mark
(if supplied) and branch name of the commit recorded into a log file
when the commit is generated.  This log can be useful to verify the
results of an import as the commits can be compared to some source
repository matching commits through the mark value.

Signed-off-by: Shawn O. Pearce <f01032651c12a22b2103346ba96b3b6b231f9d3c@spearce.org>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git