VOL-1446 : Cleanup of db/model unit tests

- Fixed issues with model components while running tests
- Removed unecessary tests

Change-Id: Ica2007b66f681d03a77144cf2e778aa5a586786a
diff --git a/db/model/non_persisted_revision.go b/db/model/non_persisted_revision.go
index 27d3d9a..cb8c9ca 100644
--- a/db/model/non_persisted_revision.go
+++ b/db/model/non_persisted_revision.go
@@ -150,8 +150,9 @@
 	GetRevCache().Lock()
 	defer GetRevCache().Unlock()
 
-	npr.Hash = npr.hashContent()
-
+	if !skipOnExist {
+		npr.Hash = npr.hashContent()
+	}
 	if _, exists := GetRevCache().Cache[npr.Hash]; !exists {
 		GetRevCache().Cache[npr.Hash] = npr
 	}