Fix diff output for renames and copies

If you use rename detection, the renamed and copied files would
not show any text diffs because the function that decides if
data should be loaded didn't know which sides of the diff to
load for those cases.

This adds a test that looks at the patch generated for diff
entries that are COPIED or RENAMED.

src/diff_output.c

@@ -593,6 +593,8 @@ static int diff_patch_load(
 		delta->new_file.flags |= GIT_DIFF_FLAG__NO_DATA;
 		break;
 	case GIT_DELTA_MODIFIED:
+	case GIT_DELTA_COPIED:
+	case GIT_DELTA_RENAMED:
 		break;
 	case GIT_DELTA_UNTRACKED:
 		delta->old_file.flags |= GIT_DIFF_FLAG__NO_DATA;

tests-clar/diff/rename.c

@@ -391,3 +391,56 @@ void test_diff_rename__working_directory_changes(void)
 
 	/* and with / without CRLF changes */
 }
+
+void test_diff_rename__patch(void)
+{
+	const char *sha0 = "2bc7f351d20b53f1c72c16c4b036e491c478c49a";
+	const char *sha1 = "1c068dee5790ef1580cfc4cd670915b48d790084";
+	git_tree *old_tree, *new_tree;
+	git_diff_list *diff;
+	git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
+	git_diff_find_options opts = GIT_DIFF_FIND_OPTIONS_INIT;
+	git_diff_patch *patch;
+	const git_diff_delta *delta;
+	char *text;
+	const char *expected = "diff --git a/sixserving.txt b/ikeepsix.txt\nindex ad0a8e5..36020db 100644\n--- a/sixserving.txt\n+++ b/ikeepsix.txt\n@@ -1,3 +1,6 @@\n+I Keep Six Honest Serving-Men\n+=============================\n+\n I KEEP six honest serving-men\n  (They taught me all I knew);\n Their names are What and Why and When\n@@ -21,4 +24,4 @@\n One million Hows, two million Wheres,\n And seven million Whys!\n \n-                -- Rudyard Kipling\n+  -- Rudyard Kipling\n";
+
+	old_tree = resolve_commit_oid_to_tree(g_repo, sha0);
+	new_tree = resolve_commit_oid_to_tree(g_repo, sha1);
+
+	diffopts.flags |= GIT_DIFF_INCLUDE_UNMODIFIED;
+	cl_git_pass(git_diff_tree_to_tree(
+		&diff, g_repo, old_tree, new_tree, &diffopts));
+
+	opts.flags = GIT_DIFF_FIND_RENAMES | GIT_DIFF_FIND_COPIES;
+	cl_git_pass(git_diff_find_similar(diff, &opts));
+
+	/* == Changes =====================================================
+	 * sixserving.txt  -> ikeepsix.txt    (copy, add title, >80% match)
+	 * sevencities.txt                    (no change)
+	 * sixserving.txt  -> sixserving.txt  (indentation change)
+	 * songofseven.txt -> songofseven.txt (major rewrite, <20% match - split)
+	 */
+
+	cl_assert_equal_i(4, (int)git_diff_num_deltas(diff));
+
+	cl_git_pass(git_diff_get_patch(&patch, &delta, diff, 0));
+	cl_assert_equal_i(GIT_DELTA_COPIED, (int)delta->status);
+
+	cl_git_pass(git_diff_patch_to_str(&text, patch));
+	cl_assert_equal_s(expected, text);
+	git__free(text);
+
+	git_diff_patch_free(patch);
+
+	cl_git_pass(git_diff_get_patch(NULL, &delta, diff, 1));
+	cl_assert_equal_i(GIT_DELTA_UNMODIFIED, (int)delta->status);
+
+	cl_git_pass(git_diff_get_patch(NULL, &delta, diff, 2));
+	cl_assert_equal_i(GIT_DELTA_MODIFIED, (int)delta->status);
+
+	cl_git_pass(git_diff_get_patch(NULL, &delta, diff, 3));
+	cl_assert_equal_i(GIT_DELTA_MODIFIED, (int)delta->status);
+
+	git_diff_list_free(diff);
+}