Default to not sync tags every time, added --rebuild-tags flag

This should speed up the time it takes to publish changes. New tags
that were not previously available will be synced but any tag that
has already been synced should be skipped.

Fixes #1

Author: simensen

README.md

@@ -103,6 +103,15 @@ tags the upstream repository knows about.
 Do not sync any tags.
 
 
+#### --rebuild-tags
+
+Ordinarily tags will not be synced more than once. This is because in general
+tags should be considered or or less static.
+
+If for some reason tags need to be resynced from scratch (history changed so
+tags might point to somewhere else) this flag will get the job done.
+
+
 #### -q,--quiet
 
 As little output as possible.

git-subsplit.sh

@@ -24,6 +24,7 @@ no-heads      do not publish any heads
 tags=         only publish for listed tags instead of all tags
 no-tags       do not publish any tags
 update        fetch updates from repository before publishing
+rebuild-tags  rebuild all tags (as opposed to skipping tags that are already synced)
 "
 eval "$(echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?)"
 
@@ -49,6 +50,7 @@ REPO_URL=
 WORK_DIR="${PWD}/.subsplit"
 HEADS=
 TAGS=
+REBUILD_TAGS=
 DRY_RUN=
 
 subsplit_main()
@@ -65,6 +67,7 @@ subsplit_main()
 			--update) UPDATE=1 ;;
 			-n) DRY_RUN="--dry-run" ;;
 			--dry-run) DRY_RUN="--dry-run" ;;
+			--rebuild-tags) REBUILD_TAGS=1 ;;
 			--) break ;;
 			*) die "Unexpected option: $opt" ;;
 		esac
@@ -178,6 +181,11 @@ subsplit_publish()
 		for TAG in $TAGS
 		do
 			LOCAL_TAG="${REMOTE_NAME}-tag-${TAG}"
+			if git branch | grep "${LOCAL_TAG}$" >/dev/null && [ -z "$REBUILD_TAGS" ]
+			then
+				say " - skpping tag ${TAG} (already synced)"
+				continue
+			fi
 			say " - syncing tag ${TAG}"
 			git branch -D "$LOCAL_TAG" >/dev/null 2>&1
 			git subtree split -q --annotate="${ANNOTATE}" --prefix="$SUBPATH" --branch="$LOCAL_TAG" "$TAG" >/dev/null 2>&1