Bugfix #1939 main_v4.1 - failure reading obs when zipped file also exists

[georgemccabe]

Same changes as PR #1941 but without the additional unit tests and test files added. See that PR for review details.

Pull Request Testing

• Describe testing already performed for these changes:
  

Similar to #1941, recreated issue and resolved it with the same changes as the develop PR.

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  

Review code changes to make sure they match the develop PR.
Ensure all automated tests pass

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [Yes]

• Do these changes include sufficient testing updates? [Yes]

• Will this PR result in changes to the test suite? [No]
  

• Please complete this pull request review by 11/15/2022.
  

Pull Request Checklist

See the METplus Workflow for details.

• Add any new Python packages to the METplus Components Python Requirements table.
• Review the source issue metadata (required labels, projects, and milestone).
• Complete the PR definition above.
• Ensure the PR title matches the feature or bugfix branch name.
• Define the PR metadata, as permissions allow.
  Select: Reviewer(s)
  Select: Organization level software support Project or Repository level development cycle Project
  Select: Milestone as the version that will include these changes
• After submitting the PR, select Development with the original issue number.
• After the PR is approved, merge your changes. If permissions do not allow this, request that the reviewer do the merge.
• Close the linked issue and delete your feature or bugfix branch from GitHub.

[jprestop]

@georgemccabe, it reviewing the code changes compared to the develop branch (https://github.com/dtcenter/METplus/pull/1941/files) it looks like there is one additional change in command_builder.py that is not here. It is on lines 739 and 740. Please review and ensure that is ok. Otherwise, all tests have passed and I approve this pull request.