Fix pylint warnings in parallel_emerge.
Fix pylint warnings in parallel_emerge.

With this change, parallel_emerge is now pylint clean.
Also update range -> xrange.

BUG=none
TEST=Verify pylint clean. Trybot run.

Change-Id: Ic249414b2553c16dc3c9fb99caed5f52cdc0d60e
Reviewed-on: https://gerrit.chromium.org/gerrit/39789
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Tested-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Ready: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>

bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,zhang0137/chromite,zhang0137/chromite,zhang0137/chromite,chadversary/chromiumos.chromite,coreos/chromite,coreos/chromite,chadversary/chromiumos.chromite,coreos/chromite,bpsinc-native/src_third_party_chromite