only write distributions file if dne

Signed-off-by: Jessica Frazelle <princess@docker.com>

hack/make/release-deb

@@ -21,7 +21,8 @@ APTDIR=$DOCKER_RELEASE_DIR/apt/repo
 mkdir -p "$APTDIR/conf" "$APTDIR/db"
 
 # create/update distributions file
-for suite in $(exec contrib/reprepro/suites.sh); do
+if [[ ! -f "$APTDIR/conf/distributions" ]]; then
+	for suite in $(exec contrib/reprepro/suites.sh); do
 		cat <<-EOF
 		Origin: Docker
 		Suite: $suite
@@ -31,7 +32,8 @@ for suite in $(exec contrib/reprepro/suites.sh); do
 		Description: Docker APT Repository
 
 		EOF
-done > "$APTDIR/conf/distributions"
+	done > "$APTDIR/conf/distributions"
+fi
 
 # set the component and priority for the version being released
 component="main"