Change method of check --set value for ability set empty values.

pym/cl_opt.py

@@ -358,7 +358,7 @@ is used in conjunction with the option '-v --vars'")
 
     def checkVarSyntax(self,values):
         """Check value of parameter set, was used for change vars"""
-        reCheckSet = re.compile("^[0-9a-z_]+=[^,]+(,[0-9a-z_]+=[^,]+)*$")
+        reCheckSet = re.compile("^[0-9a-z_]+=[^,]*(,[0-9a-z_]+=[^,]*)*$")
         if values.set:
             for val in values.set:
                 if not reCheckSet.match(val):