mrhlpr, mrtest: Add --version command

This also effectively reverts 7d068e20, because now we actually use the version for something in the program. It also avoids the problems reported in #15 (closed) to the best of my knowledge — I tried reproducing the bug as written in there and did not get any build failures.

The primary purpose of this version command is for making experimentation with mypyc easier, but I also can imagine it might be nice for users to be able to get their version of mrtest easily.

mrhlpr/frontend.py

@@ -16,6 +16,7 @@ from . import ci_labels  # type: ignore[attr-defined]
 from . import git
 from . import gitlab
 from . import mr
+from . import version
 
 
 def print_status(mr_id: int, no_cache: bool = False) -> None:
@@ -178,6 +179,9 @@ def parse_args() -> argparse.Namespace:
         action="store_true",
         help="display debug log: all git commands and" " locations of http cache files",
     )
+    parser.add_argument(
+        "-V", "--version", action="version", version=version.get_full_version_information()
+    )
     sub = parser.add_subparsers(title="action", dest="action")
     sub.required = True