test-backend: Make test coverage gaps in zerver/lib more explicit.
test-backend: Make test coverage gaps in zerver/lib more explicit.

This will make it much less likely that we'll have more regressions of
files losing 100% test coverage like push_notifications.py had
recently.

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