Clones options object to avoid mutating the original

Author: cspotcode

lib/parse.js

@@ -113,7 +113,7 @@ function parse(command, args, options) {
     }
 
     args = args ? args.slice(0) : [];  // Clone array to avoid changing the original
-    options = options || {};
+    options = options ? assign({}, options) : {}; // Clone object to avoid changing the original
 
     // Build our parsed object
     parsed = {