etree.xmlfile shadows exceptions thrown by output

[dhjt]

It looks like lxml eats any exceptions in the output that etree.xmlfile
writes into, leaving the output in a broken state. This goes unnoticed.
Only if you try to write to that same output again, things explode.

Please refer to attached testcase and the mailing list:

https://mailman-mail5.webfaction.com/pipermail/lxml/2014-December/007359.html

System info:

Python : sys.version_info(major=2, minor=7, micro=6,
releaselevel='final', serial=0)
lxml.etree : (3, 4, 0, 0)
libxml used : (2, 9, 1)
libxml compiled : (2, 7, 8)
libxslt used : (1, 1, 28)
libxslt compiled : (1, 1, 26)

[scoder (scoder)]

Rejecting as it's essentially fixed in Py3.

[scoder (scoder)]

Actually, let me take that back. The bug here is xmlfile tries to write the closing end tags in the context manager. It should not do that.
https://github.com/lxml/lxml/commit/7cb20fc92944a3db3cfd63e763536af94be15aa7