iterparse cannot parse gzip compressed files

[Funky Future]

the parsing tutorial states that gzip-compressed files can be feeded to the parser. however, it doesn't:

# BEGIN console replay
u@h:/tmp/lxml-gz $ pip install lxml
Collecting lxml
  Using cached https://files.pythonhosted.org/packages/e7/a8/40115c84414c017e1a293f331709eb7534303d3ccd11ef805ac09b1481e7/lxml-4.4.1-cp37-cp37m-manylinux1_x86_64.whl
Installing collected packages: lxml
Successfully installed lxml-4.4.1
u@h:/tmp/lxml-gz $ echo "<root/>" > test.xml
u@h:/tmp/lxml-gz $ gzip test.xml
u@h:/tmp/lxml-gz $ file text.xml.gz
text.xml.gz: gzip compressed data, was "text.xml", last modified: Sun Sep 8 18:51:23 2019, from Unix, original size 8
u@h:/tmp/lxml-gz $ python
>>> for _, el in etree.iterparse("./test.xml.gz"):
... print(el)
...
Traceback (most recent call last):
  File "<input>", line 1, in <module>
    for _, el in etree.iterparse("./test.xml.gz"):
  File "src/lxml/iterparse.pxi", line 209, in lxml.etree.iterparse.__next__
  File "src/lxml/iterparse.pxi", line 194, in lxml.etree.iterparse.__next__
  File "src/lxml/iterparse.pxi", line 229, in lxml.etree.iterparse._read_more_events
  File "src/lxml/parser.pxi", line 1364, in lxml.etree._FeedParser.feed
  File "src/lxml/parser.pxi", line 592, in lxml.etree._ParserContext._handleParseResult
  File "src/lxml/parser.pxi", line 601, in lxml.etree._ParserContext._handleParseResultDoc
  File "src/lxml/parser.pxi", line 711, in lxml.etree._handleParseResult
  File "src/lxml/parser.pxi", line 640, in lxml.etree._raiseParseError
  File "./test.xml.gz", line 1
lxml.etree.XMLSyntaxError: Document is empty, line 1, column 1
>>>
u@h:/tmp/lxml-gz $ gunzip test.xml.gz
u@h:/tmp/lxml-gz $ python
>>> from lxml import etree
>>> for _, el in etree.iterparse("./test.xml"):
... print(el)
...
<Element root at 0x7f2c530996c8>
# END console replay

# BEGIN versions info
Python : sys.version_info(major=3, minor=7, micro=3, releaselevel='final', serial=0)
lxml.etree : (4, 4, 1, 0)
libxml used : (2, 9, 9)
libxml compiled : (2, 9, 9)
libxslt used : (1, 1, 33)
libxslt compiled : (1, 1, 33)
# END versions info

there's also thois quqestion on SO: https://stackoverflow.com/questions/12902756/lxml-cant-parse-gzipped-xml