pytest: allow duplicated options.

Python dict can't have duplicate entries, but some options can be specified
multiple times.  The easiest way is to put a list in the dict.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tests/utils.py

@@ -316,6 +316,9 @@ class LightningD(TailableProc):
         for k, v in sorted(self.opts.items()):
             if v is None:
                 opts.append("--{}".format(k))
+            elif isinstance(v, list):
+                for i in v:
+                    opts.append("--{}={}".format(k, i))
             else:
                 opts.append("--{}={}".format(k, v))