Add --add option to git-repo-config

For multivars, the "git-repo-config name value ^$" is useful but
nonintuitive and troublesome to do repeatedly (since the value is not
at the end of the command line).  This commit simply adds an --add
option that adds a new value to a multivar.  Particularly useful for
tracking a new branch on a remote:

git-repo-config --add remote.origin.fetch +next:origin/next

Includes documentation and test.

Signed-off-by: Brian Gernhardt <benji@silverinsanity.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-repo-config.txt

@@ -10,6 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git-repo-config' [--global] [type] name [value [value_regex]]
+'git-repo-config' [--global] [type] --add name value
 'git-repo-config' [--global] [type] --replace-all name [value [value_regex]]
 'git-repo-config' [--global] [type] --get name [value_regex]
 'git-repo-config' [--global] [type] --get-all name [value_regex]
@@ -23,7 +24,8 @@ You can query/set/replace/unset options with this command. The name is
 actually the section and the key separated by a dot, and the value will be
 escaped.
 
-If you want to set/unset an option which can occur on multiple
+Multiple lines can be added to an option by using the '--add' option.
+If you want to update or unset an option which can occur on multiple
 lines, a POSIX regexp `value_regex` needs to be given.  Only the
 existing values that match the regexp are updated or unset.  If
 you want to handle the lines that do *not* match the regex, just
@@ -53,6 +55,10 @@ OPTIONS
 	Default behavior is to replace at most one line. This replaces
 	all lines matching the key (and optionally the value_regex).
 
+--add::
+	Adds a new line to the option without altering any existing
+	values.  This is the same as providing '^$' as the value_regex.
+
 --get::
 	Get the value for a given key (optionally filtered by a regex
 	matching the value). Returns error code 1 if the key was not
@@ -194,6 +200,12 @@ To actually match only values with an exclamation mark, you have to
 % git repo-config section.key value '[!]'
 ------------
 
+To add a new proxy, without altering any of the existing ones, use
+
+------------
+% git repo-config core.gitproxy '"proxy" for example.com'
+------------
+
 
 include::config.txt[]
 

builtin-repo-config.c

@@ -3,7 +3,7 @@
 #include <regex.h>
 
 static const char git_config_set_usage[] =
-"git-repo-config [ --global ] [ --bool | --int ] [--get | --get-all | --get-regexp | --replace-all | --unset | --unset-all] name [value [value_regex]] | --list";
+"git-repo-config [ --global ] [ --bool | --int ] [--get | --get-all | --get-regexp | --replace-all | --add | --unset | --unset-all] name [value [value_regex]] | --list";
 
 static char *key;
 static regex_t *key_regexp;
@@ -190,7 +190,9 @@ int cmd_repo_config(int argc, const char **argv, const char *prefix)
 			use_key_regexp = 1;
 			do_all = 1;
 			return get_value(argv[2], argv[3]);
-		} else if (!strcmp(argv[1], "--replace-all"))
+		} else if (!strcmp(argv[1], "--add"))
+			return git_config_set_multivar(argv[2], argv[3], "^$", 0);
+		else if (!strcmp(argv[1], "--replace-all"))
 
 			return git_config_set_multivar(argv[2], argv[3], NULL, 1);
 		else

t/t1300-repo-config.sh

@@ -265,6 +265,16 @@ EOF
 test_expect_success '--get-regexp' \
 	'git-repo-config --get-regexp in > output && cmp output expect'
 
+git-repo-config --add nextsection.nonewline "wow4 for you"
+
+cat > expect << EOF
+wow2 for me
+wow4 for you
+EOF
+
+test_expect_success '--add' \
+	'git-repo-config --get-all nextsection.nonewline > output && cmp output expect'
+
 cat > .git/config << EOF
 [novalue]
 	variable