fixed some circular references
merged branch fabpot/random-leaks (PR #8948)

This PR was merged into the 2.2 branch.

Discussion
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Fixed some random leaks

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
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970405f fixed some circular references