Merge branch 'jc/test-lazy-prereq' (early part)

* 'jc/test-lazy-prereq' (early part):
  t3419: drop unnecessary NOT_EXPENSIVE pseudo-prerequisite
  t3302: drop unnecessary NOT_EXPENSIVE pseudo-prerequisite
  t3302: do not chdir around in the primary test process
  t3302: coding style updates
  test: turn USR_BIN_TIME into a lazy prerequisite
  test: turn EXPENSIVE into a lazy prerequisite

t/test-lib.sh

@@ -976,6 +976,14 @@ test_lazy_prereq AUTOIDENT '
 	git var GIT_AUTHOR_IDENT
 '
 
+test_lazy_prereq EXPENSIVE '
+	test -n "$GIT_TEST_LONG"
+'
+
+test_lazy_prereq USR_BIN_TIME '
+	test -x /usr/bin/time
+'
+
 # When the tests are run as root, permission tests will report that
 # things are writable when they shouldn't be.
 test -w / || test_set_prereq SANITY