WmiClass: Don't share "versions" between instances

Lists in Python are mutable and when used as a default value of a
parameter for class constructor, its value will be shared between
all class instances.

Example:

	class Test:
	    def __init__(self, mylist=[]):
	        self.mylist = mylist

	A = Test()
	B = Test()
	A.mylist.append("mylist from instance A")
	print(B.mylist) # Will print ['mylist from instance A']
Reviewed-by: NDaniel P. Berrangé <berrange@redhat.com>
Signed-off-by: NRadostin Stoyanov <rstoyanov1@gmail.com>

src/hyperv/hyperv_wmi_generator.py

@@ -44,9 +44,9 @@ class WmiClass:
     to.
     """
 
-    def __init__(self, name, versions = []):
+    def __init__(self, name, versions=None):
         self.name = name
-        self.versions = versions
+        self.versions = versions if versions else list()
         self.common = None