Passing an invalid --param option in leads to a crash lower down in
the gerrit modules which can be hard to trace back to the original
error: the user forgot the "key" in the "key=value".

Change-Id: I6fe5fab0fad15cf8d25173e0f1c8ea130efc44ec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2558651Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Mike Frysinger <vapier@chromium.org>