File modes in filedescr entries are also passed to Python, so we now put "U" in there, and convert it to "rb" (or "r" for non-universal-newline builds) before passing it to fopen().
File modes in filedescr entries are also passed to Python, so we now put "U"
in there, and convert it to "rb" (or "r" for non-universal-newline builds)
before passing it to fopen().

Fixes #561326.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator