PR#1008: decode_args(): make a copy of the opts dict, rather than modifying it in-place

Merges #1008
https://pagure.io/koji/pull-request/1008

Fixes: #1007
https://pagure.io/koji/issue/1007
decode_args() might result in --package parameter missing in runroot command

koji/__init__.py

@@ -440,8 +440,8 @@ def decode_args(*args):
     if len(args) > 0:
         last = args[-1]
         if isinstance(last, dict) and last.get('__starstar', False):
-            del last['__starstar']
-            opts = last
+            opts = last.copy()
+            del opts['__starstar']
             args = args[:-1]
     return args, opts