log --pretty/--oneline: ignore log.decorate

Many scripts, most notably gitk, rely on output from the log family of
command not to be molested by random user configuration.  This is
especially true when --pretty=raw is given.

Just like we disable notes output unless the command line explicitly
asks for --show-notes, disable the decoration code unless --decorate is
given explicitly from the command line and --pretty or --oneline is
given.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin-log.c b/builtin-log.c
index 0afba31..7f4186f 100644
--- a/builtin-log.c
+++ b/builtin-log.c
@@ -53,6 +53,7 @@
 		      struct rev_info *rev)
 {
 	int i;
+	int decoration_given = 0;
 
 	rev->abbrev = DEFAULT_ABBREV;
 	rev->commit_format = CMIT_FMT_DEFAULT;
@@ -89,11 +90,13 @@
 		const char *arg = argv[i];
 		if (!strcmp(arg, "--decorate")) {
 			decoration_style = DECORATE_SHORT_REFS;
+			decoration_given = 1;
 		} else if (!prefixcmp(arg, "--decorate=")) {
 			const char *v = skip_prefix(arg, "--decorate=");
 			decoration_style = parse_decoration_style(arg, v);
 			if (decoration_style < 0)
 				die("invalid --decorate option: %s", arg);
+			decoration_given = 1;
 		} else if (!strcmp(arg, "--no-decorate")) {
 			decoration_style = 0;
 		} else if (!strcmp(arg, "--source")) {
@@ -103,6 +106,14 @@
 		} else
 			die("unrecognized argument: %s", arg);
 	}
+
+	/*
+	 * defeat log.decorate configuration interacting with --pretty
+	 * from the command line.
+	 */
+	if (!decoration_given && rev->pretty_given)
+		decoration_style = 0;
+
 	if (decoration_style) {
 		rev->show_decorations = 1;
 		load_ref_decorations(decoration_style);