Building a dependency tree has a problem

[aplteam]

When a package Foo is opened that has dependencies that themselves depend on Foo then things go awry: the principal package is not being taken into account when the build tree is compiled, leading to a wrong result.

Since this is a pretty rare scenario it did not come to light until recently. CodeCoverage is an example: for development it depends on Tester2 which in turn depends on CodeCoverage.