Fix Enum arguments that accept multiple values

EnumAction was erasing nargs before passing it to the superclass
initializer, which broke handling for arguments with consecutive values.

The help text for --desired-buyer has been updated to reflect that you
actually can specify multiple values with a single declaration now.

bonemarketsolver/__main__.py

@@ -67,7 +67,7 @@ skeleton_parameters.add_argument(
         action=EnumAction,
         nargs='+',
         type=Buyer,
-        help="specific buyer that skeleton should be designed for (if declared repeatedly, will choose from among those provided)",
+        help="specific buyer that skeleton should be designed for (if multiple are specified, will choose from among them)",
         dest='desired_buyers'
         )
 

bonemarketsolver/objects/enumaction.py

@@ -8,7 +8,7 @@ class EnumAction(Action):
         # Pop off the type value
         enum = kwargs.pop('type', None)
 
-        nargs = kwargs.pop('nargs', None)
+        nargs = kwargs.get('nargs')
 
         # Generate choices from the Enum
         kwargs.setdefault('choices', tuple(member.name.lower() for member in enum))
@@ -19,12 +19,14 @@ class EnumAction(Action):
         self._nargs = nargs
 
     def __call__(self, parser, namespace, values, option_string=None):
+        if self._nargs is None or self._nargs == '?':
             # Convert value back into an Enum
             enum = self._enum[values.upper()]
 
-        if self._nargs is None or self._nargs == '?':
             setattr(namespace, self.dest, enum)
         else:
-            items = getattr(namespace, self.dest, list())
-            items.append(enum)
+            # Convert values back into Enums
+            enums = [self._enum[value.upper()] for value in values]
+
+            items = getattr(namespace, self.dest, list()) + enums
             setattr(namespace, self.dest, items)