Merge branch 'jn/test-lint-one-shot-export-to-shell-function' into jch

The test-lint machinery knew to check "VAR=VAL shell_function"
construct, but did not check "VAR= shell_funciton", which has been
corrected.

* jn/test-lint-one-shot-export-to-shell-function:
  fetch test: mark test of "skipping" haves as v0-only
  t/check-non-portable-shell: detect "FOO= shell_func", too
  fetch test: avoid use of "VAR= cmd" with a shell function

t/check-non-portable-shell.pl

@@ -46,7 +46,7 @@ sub err {
 	/(?:\$\(seq|^\s*seq\b)/ and err 'seq is not portable (use test_seq)';
 	/\bgrep\b.*--file\b/ and err 'grep --file FILE is not portable (use grep -f FILE)';
 	/\bexport\s+[A-Za-z0-9_]*=/ and err '"export FOO=bar" is not portable (use FOO=bar && export FOO)';
-	/^\s*([A-Z0-9_]+=(\w+|(["']).*?\3)\s+)+(\w+)/ and exists($func{$4}) and
+	/^\s*([A-Z0-9_]+=(\w*|(["']).*?\3)\s+)+(\w+)/ and exists($func{$4}) and
 		err '"FOO=bar shell_func" assignment extends beyond "shell_func"';
 	$line = '';
 	# this resets our $. for each file

t/t5552-skipping-fetch-negotiator.sh

@@ -107,7 +107,11 @@ test_expect_success 'use ref advertisement to filter out commits' '
 
 	# The ref advertisement itself is filtered when protocol v2 is used, so
 	# use v0.
-	GIT_TEST_PROTOCOL_VERSION= trace_fetch client origin to_fetch &&
+	(
+		GIT_TEST_PROTOCOL_VERSION= &&
+		export GIT_TEST_PROTOCOL_VERSION &&
+		trace_fetch client origin to_fetch
+	) &&
 	have_sent c5 c4^ c2side &&
 	have_not_sent c4 c4^^ c4^^^
 '
@@ -169,7 +173,17 @@ test_expect_success 'do not send "have" with ancestors of commits that server AC
 	test_commit -C server commit-on-b1 &&
 
 	test_config -C client fetch.negotiationalgorithm skipping &&
-	trace_fetch client "$(pwd)/server" to_fetch &&
+
+	# NEEDSWORK: The number of "have"s sent depends on whether the transport
+	# is stateful. If the overspecification of the result were reduced, this
+	# test could be used for both stateful and stateless transports.
+	(
+		# Force protocol v0, in which local transport is stateful (in
+		# protocol v2 it is stateless).
+		GIT_TEST_PROTOCOL_VERSION=0 &&
+		export GIT_TEST_PROTOCOL_VERSION &&
+		trace_fetch client "$(pwd)/server" to_fetch
+	) &&
 	grep "  fetch" trace &&
 
 	# fetch-pack sends 2 requests each containing 16 "have" lines before