This won't achieve what you're describing as the `popen` call is during VM startup rather than being "frozen" at translation time.  Perhaps if you move the call to the module namespace and assign it to a const a la (untested):
````` python
GIT_REV = os.popen("git rev-parse --short HEAD", "r").readline()
# ... then, in `_entry_point`
description = "%s (ruby-%sp%d) [%s] (git rev %s)" % (engine, version, patchlevel, platform, GIT_REV)
`````