Clear PoolManager in ‘remote_connection’ to ensure sockets are closed

A fix for: https://github.com/SeleniumHQ/selenium/issues/6878

When the ‘keep alive’ option is enabled the remote_connection object will create a PoolManager, but never deliberately clear it.  This can cause ResourceWarning warnings from open sockets.

Added a new "close()" function which explicitly clears the pool.  This close function is called from Webdriver's “quit()” function (+1 squashed commit)

Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/SeleniumHQ/selenium
Cr-Mirrored-Commit: eb4a3c475c10ef0c7d65dce45fa179ce2c109e5d
2 files changed