Update image reference command

docker.mk

@@ -7,8 +7,8 @@ dockerfiles:=$(shell ls docker/build/*/Dockerfile)
 all_images:=$(patsubst docker/build/%/Dockerfile,%,$(dockerfiles))
 
 # Used in the test.mk file as well.
-images:=$(shell git diff --name-only $(TRAVIS_COMMIT_RANGE) | python util/parsefiles.py)
-
+images:=$(if $(TRAVIS_COMMIT_RANGE),$(shell git diff --name-only $(TRAVIS_COMMIT_RANGE) | python util/parsefiles.py),$(all_images))
+	
 docker_build=docker.build.
 docker_test=docker.test.
 docker_pkg=docker.pkg.