tests: unify test-bad-extension

tests/test-bad-extension.t

@@ -1,13 +1,15 b''
-#!/bin/sh
-
-echo 'raise Exception("bit bucket overflow")' > badext.py
-abspath=`pwd`/badext.py
+  $ echo 'raise Exception("bit bucket overflow")' > badext.py
+  $ abspath=`pwd`/badext.py
 
-echo '[extensions]' >> $HGRCPATH
-echo "gpg =" >> $HGRCPATH
-echo "hgext.gpg =" >> $HGRCPATH
-echo "badext = $abspath" >> $HGRCPATH
-echo "badext2 =" >> $HGRCPATH
+  $ echo '[extensions]' >> $HGRCPATH
+  $ echo "gpg =" >> $HGRCPATH
+  $ echo "hgext.gpg =" >> $HGRCPATH
+  $ echo "badext = $abspath" >> $HGRCPATH
+  $ echo "badext2 =" >> $HGRCPATH
 
-hg -q help help 2>&1 | python -c \
-  "import sys; sys.stdout.write(sys.stdin.read().replace('$abspath', '.../badext.py'))"
+  $ hg -q help help
+  \*\*\* failed to import extension badext from .*/badext.py: bit bucket overflow
+  \*\*\* failed to import extension badext2: No module named badext2
+  hg help [TOPIC]
+  
+  show help for a given topic or a help overview