Prevent graph update within the same SSA expression

Added ssa update testcases
Merge to latest
Remove reference to test file
Fix bad merge
Prevent graph update within an ssa expression

Add testcases for ssa update
Merge branch 'DSDynamoJun' of https://github.com/junmendoza/Dynamo into DSDynamoJun
Merge pull request #1189 from junmendoza/DSDynamoJun

Prevent graph update within the same SSA expression