tests: fix failures when CDPATH is set

Some tests would otherwise fail because commands such as
  cd trash/repos/foo && git rev-list --reverse HEAD | head -1
would return 2 lines instead of 1: the 'cd' command also
prints the path when CDPATH is set.

Signed-off-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

tests/setup.sh

@@ -15,6 +15,7 @@
 # run_test 'repo index' 'cgit_url "/" | tidy -e'
 # run_test 'repo summary' 'cgit_url "/foo" | tidy -e'
 
+unset CDPATH
 
 mkrepo() {
 	name=$1