[WIP] pin libxml2 at 2.9.1

[tomkralidis]

Overview

DO NOT MERGE

Test for libxml2 2.9.1 travis pinning. Looks like libxml2 2.9.4 introduces XML validation errors.

Related Issue / Discussion

Additional Information

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[tomkralidis]

cc @kalxas

Looks like is an lxml issue. 3.6.1 works, 3.6.4 breaks.

[tomkralidis]

On second thought, more testing:

• lxml 3.6.1 && libxml2 2.9.1 passes
• lxml 3.6.2 && libxml2 2.9.1 passes
• lxml 3.6.3 && libxml2 2.9.4 FAILS with said validation error
• lxml 3.6.4 && libxml2 2.9.4 FAILS with said validation error

[ricardogsilva]

It would be great if we could bump the version of lxml to 3.6.3 or higher. According to this thread on stackoverflow, and I've also tested it myself on ubuntu 16.04, lxml is now providing wheels (AKA binary downloads) on pypi. This would mean that installing lxml would be a lot faster on Travis (and everywhere else too). It would also mean that installing pycsw would be faster and with fewer external dependencies (no need for libxml2-dev and libxslt1-dev anymore).

[tomkralidis]

cc @kalxas

@ricardogsilva not sure about this one given #454. @kalxas?

[kalxas]

We have to make sure that other distributions also have this version available, not just Pypi.

[tomkralidis]

Given #454 it looks like there has not been any releases of libxml2 since this bug was addressed?

[ricardogsilva]

@tomkralidis @kalxas
FYI, libxml2 has a new release out, version 2.9.5. Perhaps this will fixes the long standing validation issues?

[kalxas]

we have to test :)

[tomkralidis]

Closing. Looks like deploys are using recent libxml2 builds.