cpython/Misc/NEWS.d/next/Library/2018-05-23-17-07-54.bpo-33625.nzQgD8.rst

Release GIL on `grp.getgrnam`, `grp.getgrgid`, `pwd.getpwnam` and
`pwd.getpwuid` if reentrant variants of these functions are available.
Patch by William Grzybowski.