Honor "tagopt = --tags" configuration option

If the "tagopt = --tags" option of a remote is set, all tags
will be fetched as in "git fetch --tags".
Signed-off-by: NSamuel Tardieu <sam@rfc1149.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1578,7 +1578,9 @@ remote.<name>.uploadpack::
 
 remote.<name>.tagopt::
 	Setting this value to \--no-tags disables automatic tag following when
-	fetching from remote <name>
+	fetching from remote <name>. Setting it to \--tags will fetch every
+	tag from remote <name>, even if they are not reachable from remote
+	branch heads.
 
 remote.<name>.vcs::
 	Setting this to a value <vcs> will cause git to interact with

contrib/examples/git-fetch.sh

@@ -127,10 +127,12 @@ then
 	orig_head=$(git rev-parse --verify HEAD 2>/dev/null)
 fi
 
-# Allow --notags from remote.$1.tagopt
+# Allow --tags/--notags from remote.$1.tagopt
 case "$tags$no_tags" in
 '')
 	case "$(git config --get "remote.$1.tagopt")" in
+	--tags)
+		tags=t ;;
 	--no-tags)
 		no_tags=t ;;
 	esac

remote.c

@@ -443,6 +443,8 @@ static int handle_config(const char *key, const char *value, void *cb)
 	} else if (!strcmp(subkey, ".tagopt")) {
 		if (!strcmp(value, "--no-tags"))
 			remote->fetch_tags = -1;
+		else if (!strcmp(value, "--tags"))
+			remote->fetch_tags = 2;
 	} else if (!strcmp(subkey, ".proxy")) {
 		return git_config_string((const char **)&remote->http_proxy,
 					 key, value);