tests/test-debugindexdot.out

Add committer tag only when needed in git conversion

Convert from a git repo added a committer: tag in the log message
even if the committer and the author were the same person.

created new head
digraph G {
	-1 -> 0
	0 -> 1
	0 -> 2
	2 -> 3
	1 -> 3
}