Make log command extensible internally (#3888)

I'm experimenting with ways to manipulate the git log that's being used to generate diffs (specifically, limiting its depth in some cases). Tweaking RepoPath for this locally isn't a huge deal but making the log command extensible seems like it could generally be useful, so I figured I'd do it.

Author: rosecodym

pkg/gitparse/gitparse.go

@@ -228,6 +228,7 @@ func (c *Parser) RepoPath(
 	abbreviatedLog bool,
 	excludedGlobs []string,
 	isBare bool,
+	additionalArgs ...string,
 ) (chan *Diff, error) {
 	args := []string{
 		"-C", source,
@@ -246,6 +247,7 @@ func (c *Parser) RepoPath(
 	} else {
 		args = append(args, "--all")
 	}
+	args = append(args, additionalArgs...) // These need to come before --
 	for _, glob := range excludedGlobs {
 		args = append(args, "--", ".", ":(exclude)"+glob)
 	}