This allows users to specify port 80 after an application has had domain added. Normally, when we first add an extra domain, the following tuple is added:
http:80:5000
A user might then want to remap port 80 to another port, such as port 8080:
dokku proxy:ports-add APP http:80:8080
The application would then have the following proxy map:
http:80:5000 http:80:8080
As nginx vhosts are resolved in FIFO order, the "correct" upstream of 8080 would basically be ignored. The workaround would be to remove the original port mapping, but the following:
dokku proxy:ports-remove APP 80
Would remove *both* entries and then re-add the default of `http:80:5000`. Thus it was not possible to use the porcelain to correct the port mapping and a user would have to fall back to using the following hack to fix their mapping:
dokku config:set APP DOKKU_PROXY_PORT_MAP='http:80:8080'
You can now use the previous syntax *as well as* the following to remove a port mapping:
dokku proxy:ports-remove APP http:80:5000
