Git does not automatically checkout the matching version of a submodule
when it checks out a new version of the parent project in the work tree.
If the submodule reference changed in the parent project then we were
reporting the submodule path as a local modification. Work around the
problem in ctest_update using "git submodule update" after "git pull".
For projects with no submodules this is a no-op. See issue #10662.
Also add a submodule to the test project for CTest.UpdateGIT to test the
work-around.
We wrap the git executable in a shell script that touches one source
file after 'git pull'. This makes the file newer than the index even
though it has not actually changed. If CTest does not refresh the index
properly then the test will fail with a bogus modified file.
Part of this test does "git pull" on a dirty work tree. We need to make
sure that 'branch.master.rebase' is false for the test repository.
Otherwise if it is true in the user configuration then pull will refuse
to rebase and the test will fail.
This creates cmCTestGIT to drive CTest Update handling on git-based work
trees. Currently we always update to the head of the remote tracking
branch (git pull), so the nightly start time is ignored for Nightly
builds. A later change will address this. See issue #6994.
Brad King