Tests: skip unsafe large header test in js_fetch.t.
diff --git a/js_fetch.t b/js_fetch.t
index 44bdbb3..126702f 100644
--- a/js_fetch.t
+++ b/js_fetch.t
@@ -432,8 +432,8 @@
 like(http_get('/chain'), qr/200 OK.*SUCCESS$/s, 'fetch chain');
 
 TODO: {
-local $TODO = 'not yet'
-	unless http_get('/njs') =~ /^([.0-9]+)$/m && $1 ge '0.7.4';
+todo_skip 'leaves coredump', 1 unless $ENV{TEST_NGINX_UNSAFE}
+	or http_get('/njs') =~ /^([.0-9]+)$/m && $1 ge '0.7.4';
 
 like(http_get('/header_iter?loc=duplicate_header_large'),
 	qr/\['A:a','B:a','C:a','D:a','E:a','F:a','G:a','H:a','Foo:a,b']$/s,