do not use 'sort' - produces different result on Windows

Might be fixable with Locale setting (https://stackoverflow.com/a/39172728), but it's easier just not to depend on it.

acceptance/bin/sort_lines.py

@@ -0,0 +1,8 @@
+#!/usr/bin/env python3
+"""
+Helper to sort lines in text file. Similar to 'sort' but no dependence on locale or presence of 'sort' in PATH.
+"""
+import sys
+lines = sys.stdin.readlines()
+lines.sort()
+sys.stdout.write("".join(lines))

acceptance/bundle/debug/script

@@ -1,3 +1,3 @@
 $CLI bundle validate --debug > out.stdout.txt 2> full.stderr.txt
 grep -vw parallel full.stderr.txt > out.stderr.txt
-grep -w parallel full.stderr.txt | sort > out.stderr.parallel.txt
+grep -w parallel full.stderr.txt | sort_lines.py > out.stderr.parallel.txt