seems to give quite opposite advice at least for official debian packages:
"Maintainers should not override the Debian Python interpreter using /usr/bin/env python or /usr/bin/env pythonX.Y. This is not advisable as it bypasses Debian's dependency checking and makes the package vulnerable to incomplete local installations of python."
Posted Feb 29, 2012 16:10 UTC (Wed) by cortana (subscriber, #24596)
[Link]
That document is aimed at Debian package maintainers. Stuff shipped by Debian is supposed to to use Debian's own Python interpreter, hence hacks like running python via env are not permitted.