graph API: fix bug in graph_is_interesting()

Previously, graph_is_interesting() did not behave quite the same way as
the code in get_revision().  As a result, it would sometimes think
commits were uninteresting, even though get_revision() would return
them.  This resulted in incorrect lines in the graph output.

This change creates a get_commit_action() function, which
graph_is_interesting() and simplify_commit() both now use to determine
if a commit will be shown.  It is identical to the old simplify_commit()
behavior, except that it never calls rewrite_parents().

This problem was reported by Santi Béjar.  The following command
would exhibit the problem before, but now works correctly:

  git log --graph --simplify-by-decoration --oneline v1.6.3.3

Previously git graph did not display the output for this command
correctly between f29ac4f and 66996ec, among other places.

Signed-off-by: Adam Simpkins <simpkins@facebook.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/t/t6015-rev-list-show-all-parents.sh b/t/t6015-rev-list-show-all-parents.sh
new file mode 100755
index 0000000000..8b146fb432
--- /dev/null
+++ b/t/t6015-rev-list-show-all-parents.sh
@@ -0,0 +1,31 @@
+#!/bin/sh
+
+test_description='--show-all --parents does not rewrite TREESAME commits'
+
+. ./test-lib.sh
+
+test_expect_success 'set up --show-all --parents test' '
+	test_commit one foo.txt &&
+	commit1=`git rev-list -1 HEAD` &&
+	test_commit two bar.txt &&
+	commit2=`git rev-list -1 HEAD` &&
+	test_commit three foo.txt &&
+	commit3=`git rev-list -1 HEAD`
+	'
+
+test_expect_success '--parents rewrites TREESAME parents correctly' '
+	echo $commit3 $commit1 > expected &&
+	echo $commit1 >> expected &&
+	git rev-list --parents HEAD -- foo.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_expect_success '--parents --show-all does not rewrites TREESAME parents' '
+	echo $commit3 $commit2 > expected &&
+	echo $commit2 $commit1 >> expected &&
+	echo $commit1 >> expected &&
+	git rev-list --parents --show-all HEAD -- foo.txt > actual &&
+	test_cmp expected actual
+	'
+
+test_done