test: remove unused test_external and test_external_without_stderr

They've been unused since their introduction in commit 0083854b12
("Copy test framework from Git"), only causing maintenance burden.

test/test-lib.sh

@@ -962,65 +962,6 @@ test_expect_code () {
 	fi
 }
 
-# test_external runs external test scripts that provide continuous
-# test output about their progress, and succeeds/fails on
-# zero/non-zero exit code.  It outputs the test output on stdout even
-# in non-verbose mode, and announces the external script with "* run
-# <n>: ..." before running it.  When providing relative paths, keep in
-# mind that all scripts run in "trash directory".
-# Usage: test_external description command arguments...
-# Example: test_external 'Perl API' perl ../path/to/test.pl
-test_external () {
-	test "$#" = 4 && { prereq=$1; shift; } || prereq=
-	test "$#" = 3 ||
-	error >&6 "bug in the test script: not 3 or 4 parameters to test_external"
-	test_subtest_name="$1"
-	shift
-	test_reset_state_
-	if ! test_skip "$test_subtest_name" "$@"
-	then
-		# Announce the script to reduce confusion about the
-		# test output that follows.
-		say_color "" " run $test_count: $descr ($*)"
-		# Run command; redirect its stderr to &4 as in
-		# test_run_, but keep its stdout on our stdout even in
-		# non-verbose mode.
-		"$@" 2>&4
-		if [ "$?" = 0 ]
-		then
-			test_ok_
-		else
-			test_failure_ "$@"
-		fi
-	fi
-}
-
-# Like test_external, but in addition tests that the command generated
-# no output on stderr.
-test_external_without_stderr () {
-	# The temporary file has no (and must have no) security
-	# implications.
-	tmp="$TMPDIR"; if [ -z "$tmp" ]; then tmp=/tmp; fi
-	stderr="$tmp/git-external-stderr.$$.tmp"
-	test_external "$@" 4> "$stderr"
-	[ -f "$stderr" ] || error "Internal error: $stderr disappeared."
-	test_subtest_name="no stderr: $1"
-	shift
-	if [ ! -s "$stderr" ]; then
-		rm "$stderr"
-		test_ok_
-	else
-		if [ "$verbose" = t ]; then
-			output=`echo; echo Stderr is:; cat "$stderr"`
-		else
-			output=
-		fi
-		# rm first in case test_failure exits.
-		rm "$stderr"
-		test_failure_ "$@" "$output"
-	fi
-}
-
 # This is not among top-level (test_expect_success)
 # but is a prefix that can be used in the test script, like:
 #