Using sys.stdout as keyword default messes up stdout capture for downstream packages

[bnavigator]

Keyword defaults are evaluated at import time, not at call time. This makes trying to capture sys.stdout output of isort.api calls with show_diff=True difficult. (regression through #1189)

https://github.com/timothycrosley/isort/blob/447580671b2e37a21a3cf1a4d2e80c387f9af98a/isort/format.py#L31-L33

See also
gforcada/flake8-isort#92 (comment)

[timothycrosley]

Thanks for reporting this issue and your great work on fixing flake8-isort compatibility! I've fixed the regression in the 5.1.4 patch release, and I think fixed the underlying issue of there being no official mechanism to capture the diff in development slated for the 5.2.0 release: #1335

Thanks!

~Timothy