Backport the fix for lp:1401130 to 1.21 - networker is disabled for joyent environments
Merge pull request #1309 from dimitern/lp-1401130-disable-networker-on-joyent-1.21

Backport the fix for lp:1401130 to 1.21 - networker is disabled for joyent environments

No changes other than backporting #1308 for 1.21.

(Review request: http://reviews.vapour.ws/r/624/)