Deprecation Warning: the imp module is deprecated in favour of importlib

[yonas]

Checkout of HEAD from today.

$ make oss
  SAPLING_OSS_BUILD=true HGNAME=sl \
  /usr/local/bin/python3 setup_with_version.py  \
  build_interactive_smartlog \
  build_py -c -d . \
  build_clib  \
  build_ext  -i \
  build_rust_ext -i -l  \
  build_pyzip -i \
  build_mo
/sapling/eden/scm/setup.py:31: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
  import imp
  ...