Merge branch 'sg/reflog-past-root' into maint

"git reflog" stopped upon seeing an entry that denotes a branch
creation event (aka "unborn"), which made it appear as if the
reflog was truncated.

* sg/reflog-past-root:
  reflog: continue walking the reflog past root commits

reflog-walk.c

@@ -241,6 +241,12 @@ void fake_reflog_parent(struct reflog_walk_info *info, struct commit *commit)
 		logobj = parse_object(reflog->osha1);
 	} while (commit_reflog->recno && (logobj && logobj->type != OBJ_COMMIT));
 
+	if (!logobj && commit_reflog->recno >= 0 && is_null_sha1(reflog->osha1)) {
+		/* a root commit, but there are still more entries to show */
+		reflog = &commit_reflog->reflogs->items[commit_reflog->recno];
+		logobj = parse_object(reflog->nsha1);
+	}
+
 	if (!logobj || logobj->type != OBJ_COMMIT) {
 		commit_info->commit = NULL;
 		commit->parents = NULL;

t/t1401-symbolic-ref.sh

@@ -110,7 +110,7 @@ test_expect_success 'symbolic-ref writes reflog entry' '
 	update
 	create
 	EOF
-	git log --format=%gs -g >actual &&
+	git log --format=%gs -g -2 >actual &&
 	test_cmp expect actual
 '
 

t/t1410-reflog.sh

@@ -348,4 +348,26 @@ test_expect_success 'reflog expire operates on symref not referrent' '
 	git reflog expire --expire=all the_symref
 '
 
+test_expect_success 'continue walking past root commits' '
+	git init orphanage &&
+	(
+		cd orphanage &&
+		cat >expect <<-\EOF &&
+		HEAD@{0} commit (initial): orphan2-1
+		HEAD@{1} commit: orphan1-2
+		HEAD@{2} commit (initial): orphan1-1
+		HEAD@{3} commit (initial): initial
+		EOF
+		test_commit initial &&
+		git reflog &&
+		git checkout --orphan orphan1 &&
+		test_commit orphan1-1 &&
+		test_commit orphan1-2 &&
+		git checkout --orphan orphan2 &&
+		test_commit orphan2-1 &&
+		git log -g --format="%gd %gs" >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done