Remove MP Finalize if cov didnt initialize.

There may be cases where cov_core_init.init() returns
None. Currently, multiprocessing_finish raises an AttributeError.

Author: alisaifee

cov-core/cov_core.py

@@ -10,9 +10,10 @@
 
 def multiprocessing_start(obj):
     cov = cov_core_init.init()
-    import multiprocessing.util
-    multiprocessing.util.Finalize(
-        None, multiprocessing_finish, args=(cov,), exitpriority=1000)
+    if cov:
+        import multiprocessing.util
+        multiprocessing.util.Finalize(
+            None, multiprocessing_finish, args=(cov,), exitpriority=1000)
 
 
 def multiprocessing_finish(cov):