Merge pull request
#3834 from ivanov/nbconvert-better-tests...
Merge pull request
#3834 from ivanov/nbconvert-better-tests
This PR fixes a few issues with nbconvert tests
The code for testing 'ipython nbconvert' prior to this PR did not work as
intended, and simply swallowed errors when pandoc wasn't installed, for example.
This PR adds a new get_output_error_code utility for easier checking of error
(looking at return code as opposed to the contents of stdout for the word
'error').
This new machinery is leveraged when calling nbconvert during tests.
