Source control commandlets do not consistently check provider status for read only or checkout and instead rely on read only state of files

Using github source control provider:

• Run a batch save commandlet from UResavePackagesCommandlet on some file that will need to fix up redirectors

Actual -> save commandlet fails to commit all the changed files, since files that had redirectors fixed up were not added to the list of those affected
Expected -> the full set of modified files are committed