Junction in junction requires top level junction

Summary

If I have projectA that junctions projectB and projectB junctions projectC then bst will not resolve until projectA also contains a junction to projectC

This is so that projectA can co-ordinate all junctions to projectC but in this case it is not needed.

We should also have a way to turn off co-ordinating junctions if it is not required or is a hindrance, in some use cases.

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