Dockerfile: use bash as default command, remove DOCKER_CLI_SHELL

Bash is installed already, so we might as well use it as a default.

This also removes the DOCKER_CLI_SHELL variable, which  was added
in  b039db985a to allow using bash
instead of (a)sh. Now that Bash is the default, there should be
no need to override, and we can keep things simple.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docker.Makefile

@@ -6,7 +6,6 @@
 
 # Overridable env vars
 DOCKER_CLI_MOUNTS ?= -v "$(CURDIR)":/go/src/github.com/docker/cli
-DOCKER_CLI_SHELL ?= ash
 DOCKER_CLI_CONTAINER_NAME ?=
 DOCKER_CLI_GO_BUILD_CACHE ?= y
 
@@ -102,7 +101,7 @@ plugins-osx: build_cross_image ## build the example CLI plugins for macOS
 dev: build_docker_image ## start a build container in interactive mode for in-container development
 	$(DOCKER_RUN) -it \
 		-v /var/run/docker.sock:/var/run/docker.sock \
-		$(DEV_DOCKER_IMAGE_NAME) $(DOCKER_CLI_SHELL)
+		$(DEV_DOCKER_IMAGE_NAME)
 
 shell: dev ## alias for dev
 

dockerfiles/Dockerfile.dev

@@ -24,7 +24,7 @@ RUN  apk add --no-cache \
     curl \
     git
 
-CMD sh
+CMD bash
 ENV DISABLE_WARN_OUTSIDE_CONTAINER=1
 ENV PATH=$PATH:/go/src/github.com/docker/cli/build