t7006: replace dubious test

The idea of the test case "git -p - core.pager is not used from subdirectory" was to verify that the setup_git_directory() function had not been called just to obtain the core.pager setting. However, we are about to fix the early config machinery so that it *does* work, without messing up the global state. Once that is done, the core.pager setting *will* be used, even when running from a subdirectory, and that is a Good Thing. The intention of that test case, however, was to verify that the setup_git_directory() function has not run, because it changes global state such as the current working directory. To keep that spirit, but fix the incorrect assumption, this patch replaces that test case by a new one that verifies that the pager is run in the subdirectory, i.e. that the current working directory has not been changed at the time the pager is configured and launched, even if the `rev-parse` command requires a .git/ directory and *will* change the working directory. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>