As documented in [RunningTests], tests have to be written to be
independent of any php.ini file.
The test expects the environment variable be set both in $_SERVER and in
$_ENV and therefore requires both.
Fix is to set `variables_order` to `ES`.
[RunningTests]: docs/source/miscellaneous/running-tests.rst

As documented in [RunningTests], tests have to be written to be
independent of any php.ini file.
As the tests are based on counting the line terminators, the
mail.add_x_header php.ini setting has to be off.
Fix is to set `mail.add_x_header` to `off`.
[RunningTests]: docs/source/miscellaneous/running-tests.rst
fix-up-of: phpGH-19188 

As documented in [RunningTests], tests have to be written to be
independent of any php.ini file.
Without specifying the timezone, the var_dump() will make use of the
default timezone that may not be the expected "UTC" timezone.
This renders the test-cases flaky and will make them fail if the
`date.timezone` is different from the string "UTC".
Fix is to interpolate the timezone in the test fixture or to set
`date.timezone` to `UTC`.
[RunningTests]: docs/source/miscellaneous/running-tests.rst