t7006: replace dubious test

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>