setup-production: Try to fix Travis failures by blocking mongodb repo.
setup-production: Try to fix Travis failures by blocking mongodb repo.

It appears the mongodb repo is not accessible by Travis CI right now.
This is sadly our problem, because Travis puts a bunch of crap in
their apt `sources.list` file, so `apt-get update` starts failing.

Galexrt/zulip,kou/zulip,brainwane/zulip,dhcrzf/zulip,rht/zulip,eeshangarg/zulip,mahim97/zulip,andersk/zulip,shubhamdhama/zulip,timabbott/zulip,rht/zulip,tommyip/zulip,synicalsyntax/zulip,mahim97/zulip,Galexrt/zulip,brainwane/zulip,rishig/zulip,timabbott/zulip,Galexrt/zulip,brockwhittaker/zulip,zulip/zulip,timabbott/zulip,Galexrt/zulip,timabbott/zulip,rht/zulip,synicalsyntax/zulip,tommyip/zulip,showell/zulip,brockwhittaker/zulip,tommyip/zulip,dhcrzf/zulip,andersk/zulip,synicalsyntax/zulip,shubhamdhama/zulip,kou/zulip,mahim97/zulip,rht/zulip,timabbott/zulip,dhcrzf/zulip,eeshangarg/zulip,brainwane/zulip,andersk/zulip,kou/zulip,dhcrzf/zulip,zulip/zulip,zulip/zulip,hackerkid/zulip,Galexrt/zulip,rishig/zulip,synicalsyntax/zulip,eeshangarg/zulip,brainwane/zulip,tommyip/zulip,timabbott/zulip,jackrzhang/zulip,synicalsyntax/zulip,punchagan/zulip,zulip/zulip,punchagan/zulip,Galexrt/zulip,zulip/zulip,shubhamdhama/zulip,showell/zulip,punchagan/zulip,punchagan/zulip,rishig/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,brainwane/zulip,mahim97/zulip,showell/zulip,jackrzhang/zulip,andersk/zulip,mahim97/zulip,brockwhittaker/zulip,kou/zulip,rishig/zulip,showell/zulip,rht/zulip,andersk/zulip,tommyip/zulip,showell/zulip,shubhamdhama/zulip,showell/zulip,jackrzhang/zulip,dhcrzf/zulip,hackerkid/zulip,hackerkid/zulip,synicalsyntax/zulip,Galexrt/zulip,timabbott/zulip,shubhamdhama/zulip,hackerkid/zulip,rht/zulip,showell/zulip,punchagan/zulip,punchagan/zulip,rishig/zulip,jackrzhang/zulip,brainwane/zulip,hackerkid/zulip,dhcrzf/zulip,punchagan/zulip,jackrzhang/zulip,tommyip/zulip,brockwhittaker/zulip,jackrzhang/zulip,eeshangarg/zulip,hackerkid/zulip,mahim97/zulip,kou/zulip,brockwhittaker/zulip,brockwhittaker/zulip,brainwane/zulip,shubhamdhama/zulip,rishig/zulip,hackerkid/zulip,shubhamdhama/zulip,synicalsyntax/zulip,zulip/zulip,eeshangarg/zulip,rishig/zulip,dhcrzf/zulip,tommyip/zulip,jackrzhang/zulip,eeshangarg/zulip,kou/zulip,kou/zulip,zulip/zulip,andersk/zulip