Miscellaneous things caught be clang-analyzer.
Some slight tweaks to how I wanted to handle cleanup in the compress_hdu function
Merge pull request #20 from embray/misc/clang-analyzer

Some slight tweaks to how I wanted to handle cleanup in the compress_hdu...
Add another unused assignment.
Merge pull request #2351 from mdboom/misc/clang-analyzer

Miscellaneous things caught by clang-analyzer.