* Check for modified paths between commits

Also expanding partial commit ids, and added new tests.
Resolves #4
Resolves #7

* Test for new commits and if repo is shallow clone

Returns Err opening a shallow clone by id
Resolves #2
Resolves #9

Adding lots of tests too

* Shallow repo check for partial commit id expansion

We can't reliably expand w/o full git history
Updated tests to check both cases

* Updating test to use fresh clones

Github is shallow cloning for Actions
Makes my tests fail...