[Mailer] STDOUT blocks infinitely under Windows when STDERR is filled

[TemaYud]

Q	A
Branch?	5.4
Bug fix?	yes
New feature?	no
Deprecations?	no
Tickets	-
License	MIT
Doc PR	-

stream_get_contents() on STDOUT blocks infinitely under Windows when STDERR is filled under some circumstances. Open STDERR in append mode ("a"), then this will work.

[carsonbot]

Hey!

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Carsonbot

[nicolas-grekas]

The failures look related, maybe this should be done only on Windows?

'\\' === \DIRECTORY_SEPARATOR ? 'a' : 'w'

[nicolas-grekas]

Thank you @TemaYud.