py3: don’t subscript socket.error
On Python 2, socket.error was subscriptable. On Python 3, socket.error is an
alias to OSError and is not subscriptable. The except block passes the
exception to self.send_error(). This fails on both Python 2 (if it was
executed) and Python 3, as it expects a string.
Getting the attribute .strerror works on Python 2 and Python 3, and has the
same effect as the previous code on Python 2.
# Files that just need to be migrated to the formatter.
# Do not add new files here!
mercurial/cext/manifest.c
mercurial/cext/osutil.c
# Vendored code that we should never format:
syntax: glob
contrib/python-zstandard/**.c
contrib/python-zstandard/**.h
hgext/fsmonitor/pywatchman/**.c
mercurial/thirdparty/**.c
mercurial/thirdparty/**.h
mercurial/pythoncapi_compat.h