Use regular string ops, instead of urlparse.urljoin.
Use regular string ops, instead of urlparse.urljoin.

urlparse.urljoin('scheme:foo/bar/', 'baz') == 'baz', so it doesn't work the
way I expected. Instead, let's use regular string joins.

BUG=chromium-os:5311
TEST=Ran buildbot in test mode.

Change-Id: Iea4205573db602e0cc20af24a77d255d17e79221

Review URL: http://codereview.chromium.org/5357012

vmware/coreos-scripts,mischief/scripts,mjg59/scripts,BugRoger/scripts,andrejro/coreos--scripts,andrejro/coreos--scripts,glevand/coreos--scripts,smilart/scripts,marineam/coreos-scripts,vmware/coreos-scripts,zhang0137/scripts,fivethreeo/scripts,vmware/coreos-scripts,zhang0137/scripts,bcwaldon/coreos-scripts,endocode/scripts,mischief/scripts,BugRoger/scripts,marineam/coreos-scripts,sigma/coreos-scripts,bcwaldon/coreos-scripts,BugRoger/scripts,bcwaldon/coreos-scripts,endocode/scripts,trnubo/scripts,andrejro/coreos--scripts,gtank/scripts,sigma/coreos-scripts,zhang0137/scripts,nicescale/scripts,coreos/scripts,mischief/scripts,mjg59/scripts,glevand/coreos--scripts,endocode/scripts,sigma/coreos-scripts,nicescale/scripts,trnubo/scripts,trnubo/scripts,smilart/scripts,marineam/coreos-scripts,mjg59/scripts,coreos/scripts,fivethreeo/scripts,gtank/scripts,fivethreeo/scripts,smilart/scripts,crawford/scripts,nicescale/scripts,crawford/scripts,crawford/scripts,gtank/scripts