Lame attempt to act like "make" even with docker images.

Makefile

@@ -13,11 +13,12 @@ endif
 all:
 ifeq (,$(shell docker image ls -q ${BASE_IMAGE}))
 	-docker container rm -f ${BOOT_CONTAINER}
-	-docker image     rm -f ${BOOT_IMAGE}
+ifeq (,$(shell docker image ls -q ${BOOT_IMAGE}))
 	rm -rf fs
 	mkdir fs
 	sudo /usr/sbin/deboot --foreign jessie fs
 	sudo tar -C fs -c . | docker import - ${BOOT_IMAGE}
+endif
 	sudo rm -rf fs
 	mkdir fs
 	tar -C fs -xf ${XILINX_TARBALL}
@@ -41,4 +42,8 @@ clean:
 	git clean -dfx -e ${XILINX_TARBALL} -e ${XILINX_LICENSE}
 	-docker container rm -f ${BOOT_CONTAINER}
 
-.PHONY: all clean
+sandblast: clean
+	-docker image rm -f ${BOOT_IMAGE}
+	-docker image rm -f ${BASE_IMAGE}
+
+.PHONY: all clean sandblast