CppunitTest testFlipAndRotateCustomShape failing on certain setups

[Luke Benes]

My desktop and @39 have been failing ever since the additional Unit Tests were enabled with
https://cgit.freedesktop.org/libreoffice/core/commit/?id=3f7e8ddea89f6340cd18b5b34f5a7c5f503962be

Here is a sample of @39 failure:
https://tinderbox.libreoffice.org/cgi-bin/gunzip.cgi?tree=MASTER&full-log=1562722611.14107

I'm seeing the same on my desktop:

H:/cygwin/home/Luke/lode/dev/core/test/source/xmltesttools.cxx(168) : error : Assertion
Test name: testFlipAndRotateCustomShape::Import_Export_Import
equality assertion failed
- Expected: 2351
- Actual  : 2352
- In <file:///H:/cygwin/tmp/lu154407xzjsn.tmp>, attribute 'x' of '//a:custGeom/a:pathLst/a:path/a:lnTo[1]/a:pt' incorrect value.

Failures !!!
Run: 112   Failure total: 1   Failures: 1   Errors: 0

Error: a unit test failed, please do one of:
make CppunitTest_sw_ooxmlexport7 CPPUNITTRACE=TRUE # which is a shortcut for the following line

Oddly my laptop with the same configuration (no configure options) passes this test.