[MatthewWilkes]

So, there's a couple of interesting bits of context. Firstly, the way these dodgy cables try and suck more juice out of sockets is by putting passives between the data lines to trick the phone into a genuine OEM charger from the same manufacturer, so it ignores the USB power specs.

Secondly, the way USB declares that something is a host is by tying ground to the sheath.

So, there's precedent for tying things together (through a passive), and tying things to ground (but only things that are floating). MY guess is that they bought some connectors designed for USB host that had the sheath tied to ground and in their attempts to tie D+ and D- together shorted to ground. Only a guess though, you really don't want to do this.