When I run test-hotspot-gtest on my Linux machine I get the following failure:
[ RUN ] LogDecorations.iso8601_utctime_test
/localhome/hg/jdk9-hs/hotspot/test/native/logging/test_logDecorations.cpp:179: Failure
Value of: trailing_character
  Actual: '.' (46, 0x2E)
Expected: 'Z'
Which is: 'Z' (90, 0x5A)
Invalid offset: 2016-11-04T10:02:38.793+0000

If I run with LC_ALL=C it works. My current locale settings are:

$ locale
LANG=en_US.UTF-8
LANGUAGE=en_US.UTF-8
LC_CTYPE="en_US.UTF-8"
LC_NUMERIC=sv_SE.UTF-8
LC_TIME=sv_SE.UTF-8
LC_COLLATE="en_US.UTF-8"
LC_MONETARY=sv_SE.UTF-8
LC_MESSAGES="en_US.UTF-8"
LC_PAPER=sv_SE.UTF-8
LC_NAME=sv_SE.UTF-8
LC_ADDRESS=sv_SE.UTF-8
LC_TELEPHONE=sv_SE.UTF-8
LC_MEASUREMENT=sv_SE.UTF-8
LC_IDENTIFICATION=sv_SE.UTF-8
LC_ALL=

This needs to be fixed, either in the test or by making sure the test is always run with LC_ALL=C.