run-tests: enforce the drive letter from `getcwd` to upper case For some reason os.getcwd() can return either `c:` or `C:` depending of which binary you used on Windows. We normalize this to `C:` and the like. This fix `test-run-tests.t` on windows as the drive letter in "$TESTTMP" was "wrongly" set to 'c:/' if the test path wasn't explicitly specified. Differential Revision: https://phab.mercurial-scm.org/D11035