storage mount fails most of the time with usbsdmux

[jan-kiszka]

We are too fast with trying to mount a partition, it seems. I'm getting most of the time

# mtda-cli storage mount 1
'storage mount' failed!

for a partition on an usbsdmux-managed card. And that even when the mux is set to host already. mtda is unconditionally switching the muxer mode on mount, right? This seems to trigger some re-plugging of the card on the host, and udev is still running while mounting is already attempted.

Simply adding some sleep to the switch may mitigate, but I'm unsure if that issues is actually generic, not limited to usbsdmux. And it is also hard to define a reasonable waiting time (specifically given how slow the process is already).