Prevent network issues due to xml.xsd

[gmessier]

Possible fix #6228

[gmessier]

Ok... I though the changes was so small that I didn't have to understand the pipeline and run tests locally... but seems I will need to dig into it.

[weirdan]

I suspect file paths in xsd may be resolved relative to cwd, which would be quite a pain to fix for PHAR.

[gmessier]

For reference: https://stackoverflow.com/questions/22774425/attempting-to-connect-xml-files-with-xinclude-attribute-xmlbase-error
I still try to find another way to be still be able to include file in another directory, but still not need to load the XML schema from the internet (so be able to load it from the PHAR that seems impossible for now).

[gmessier]

The only solution I could find is to allow any attribute to be set in the configuration. XInclude will be able to add the xml:base attribute without breaking the schema validation. It should not be a big problem to allow useless attributes, but it's not to me to take this decision.
The only other solution I can see is to remove this feature and not be able to include file from other directory. IMO if you can only include files from the same directory it's not so useful. It only "clean" a little bit your configuration by having many files with small chunks of the configuration (by example one for the projectFiles, one for the issueHandlers, etc.)

[weirdan]

Thanks!