xpi-repack: Print meaningful error message when --upstream-version is missing.

Closes: #740762

1 files changed, 3 insertions, 0 deletions

diff --git a/xpi-repack b/xpi-repack
index 9b9663b..b43f02b 100755
--- a/xpi-repack
+++ b/xpi-repack
@@ -92,6 +92,9 @@ def main():
 
     if not args.package:
         args.package = get_source_package_name(script_name)
+    if not args.version:
+        parser.error("Unknown upstream version. "
+                     "You have to specify one with --upstream-version.")
 
     repack_xpi(script_name, args.package, args.version, args.xpi_file,
                args.verbose)