Add tests for a few A-needstest issues

Closes #7813.
Closes #10902.
Closes #11374.
Closes #11714.
Closes #12920.
Closes #13202.
Closes #13624.
Closes #14039.
Closes #15730.
Closes #15783.
auto merge of #17199 : jakub-/rust/issues-that-need-tests, r=alexcrichton

Closes #7813.
Closes #10902.
Closes #11374.
Closes #11714.
Closes #12920.
Closes #13202.
Closes #13624.
Closes #14039.
Closes #15730.
Closes #15783.