bash giving an error to stdout causes tests to fail

======================================================================
FAIL: test01_local (gridtk.tests.GridTKTest)
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Traceback (most recent call last):
  File "/local/gitlab-runner/builds/6b02994f/2/bob/gridtk/env/lib/python2.7/site-packages/gridtk/tests/__init__.py", line 168, in test01_local
    self.assertEqual(open(err_file).read().split('\n')[0], 'This is a text message to std-err')
AssertionError: '/bin/bash: /local/conda/envs/bob-devel-py27/lib/libtinfo.so.5: no version information available (required by /bin/bash)' != 'This is a text message to std-err'

The script that runs is this:

#!/bin/bash

# We simply write one line to stdout and one line to stderr
echo "This is a text message to std-out"
echo "This is a text message to std-err" >&2

# We exit with -1 (should be 255 as the "result")
exit -1

But looks like there is a problem with bash here.