Use subprocess timeout by ngie-eign · Pull Request #2127 · gitpython-developers/GitPython

subprocess's APIs in 3.3+ support passing timeout to calls, such as
.communicate(..), .wait(..), etc. Pass `kill_after_timeout` to those
APIs and remove the watchdog handler code as it's not needed once
`timeout=` is used.

This enables `kill_after_timeout` on Windows platforms by side-effect as
upstream implements `timeout` for all supported platforms.

Signed-off-by: Enji Cooper <yaneurabeya@gmail.com>