setting XML_CATALOG_FILES environment variable ignored by lxml 3.4.4

[ian]

Windows 7, 64 bit, using the whl from the "Unofficial Windows Binaries for Python Extension Packages"

Using os.environ['XML_CATALOG_FILES'] in a script sets the environment variable correctly (I assume, as os.getenv returns the expected content), but when the variable is used by lxml, the following error is reported:
  File "lxml.etree.pyx", line 3310, in lxml.etree.parse (src\lxml\lxml.etree.c:72517)
  File "parser.pxi", line 1791, in lxml.etree._parseDocument (src\lxml\lxml.etree.c:105979)
  File "parser.pxi", line 1817, in lxml.etree._parseDocumentFromURL (src\lxml\lxml.etree.c:106278)
  File "parser.pxi", line 1721, in lxml.etree._parseDocFromFile (src\lxml\lxml.etree.c:105277)
  File "parser.pxi", line 1122, in lxml.etree._BaseParser._parseDocFromFile (src\lxml\lxml.etree.c:100227)
  File "parser.pxi", line 580, in lxml.etree._ParserContext._handleParseResultDoc (src\lxml\lxml.etree.c:94350)
  File "parser.pxi", line 690, in lxml.etree._handleParseResult (src\lxml\lxml.etree.c:95786)
  File "parser.pxi", line 620, in lxml.etree._raiseParseError (src\lxml\lxml.etree.c:94853)
lxml.etree.XMLSyntaxError: failed to load external entity "file:/E:/tmp/Main/map.dtd", line 2, column 61

The final line of which means that the catalog referenced by the environment variable is not being used.
This is run with the following:
Python : sys.version_info(major=3, minor=4, micro=3, releaselevel='final', serial=0)
lxml.etree : (3, 4, 4, 0)
libxml used : (2, 9, 2)
libxml compiled : (2, 9, 2)
libxslt used : (1, 1, 28)
libxslt compiled : (1, 1, 28)

* setting the variable is the DOS shell before running the script does not encounter this error.
* running the same script with an earlier version of lxml works as expected:
   Python : sys.version_info(major=3, minor=4, micro=3, releaselevel='final', serial=0)
   lxml.etree : (3, 3, 5, 0)
   libxml used : (2, 9, 1)
   libxml compiled : (2, 9, 1)
   libxslt used : (1, 1, 28)
   libxslt compiled : (1, 1, 28)

[scoder (scoder)]

Using "os.environ" to set an environment variable only applies to processes being started as subprocesses later on, not to the current process itself. I therefore cannot imagine that this ever worked. Most likely, there's something else that differs between the two installations on your side.

[ian (ianbalanza)]

As I said, yes this did work as I was able to see default attribute values drawn from the DITA DTDs referenced through the catalog.

[scoder (scoder)]

I wasn't questioning that it worked in your specific setup. I was questioning that it worked *because of* the older lxml version.

[scoder (scoder)]

Closing as outdated.