log when koji authentication fails

gwkoji/packager.py

@@ -193,7 +193,11 @@ def main():
     # how do we determine this when source is from git?
 
     # check that we can authenticate to koji
-    koji.moshimoshi(logger=logger)
+    try:
+        koji.moshimoshi(logger=logger)
+    except subprocess.CalledProcessError:
+        logger.critical("unable to authenticate with koji server")
+        raise
 
     # determine if the package is already registered with koji
     if args.source_type != "git":