docker: do not invalidate the system container when changing reference

Author: illwieckz

docker-build

@@ -183,7 +183,7 @@ def main():
         targets_env="--env=targets={}".format(" ".join(common_target_list))
 
         # Install Debian and dependencies.
-        docker.run("build", ["unvanquished-common-system", targets_arg, reference_arg])
+        docker.run("build", ["unvanquished-common-system", targets_arg])
 
         # Clone source repositories and build external dependencies.
         docker.run("build", ["unvanquished-common-source", targets_arg, reference_arg])
@@ -202,7 +202,7 @@ def main():
             stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)
 
         # Install Ubuntu, Darling, Xcode and other dependencies.
-        docker.run("build", ["unvanquished-darling-system", targets_arg, reference_arg])
+        docker.run("build", ["unvanquished-darling-system", targets_arg])
 
         after, err = docker.run("inspect", inspect_system_command_list,
             stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)

docker/unvanquished-common-system.Dockerfile

@@ -11,9 +11,6 @@ RUN test -n "${targets}"
 COPY docker/install-system-dependencies /docker
 RUN /docker/install-system-dependencies
 
-ARG reference
-RUN test -n "${reference}"
-
 COPY docker/clone-repositories /docker
 
 COPY docker/build-external-dependencies /docker

docker/unvanquished-darling-system.Dockerfile

@@ -11,9 +11,6 @@ RUN test -n "${targets}"
 COPY docker/install-system-dependencies /docker
 RUN /docker/install-system-dependencies
 
-ARG reference
-RUN test -n "${reference}"
-
 COPY docker/clone-repositories /docker
 
 COPY docker/build-targets /docker