Do not use shallow clones for source-repository-packages

[9999years]

Fixes #10605

Includes a regression test.

• Patches conform to the coding conventions.
• Any changes that could be relevant to users have been recorded in the changelog.
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• The documentation has been updated, if necessary.
• Manual QA notes have been included.
• Tests have been added. (Ask for help if you don’t know how to write them! Ask for an exemption if tests are too complex for too little coverage!)

[philderbeast]

I checked out this branch, installed cabal-install from it and reran a timing test against amazonka, same as #10605 (comment). This gives slow results. I ran it twice after cleaning and got 82s and 84s. I reran the same test twice using cabal-install from the master branch, at 1f52963, and got times of, 16s each time.

[9999years]

@philderbeast Yes, that's what I'm expecting. It might be possible to keep the shallow clone behavior in some cases without introducing regressions, but let's fix the regressions first.