getvar: fix broken 'fastboot flash' when partition has slots

Stuck FastBoot Mode fastboot getvar currentslot and via fastboot: fastboot getvar current-slot At any time we can switch to the next inactive slot using: fastboot set_active other , or we can use: fastboot fastboot getvar currentslot error: Failed to identify current slot Diffing the results of fastboot getvar all with SD card, compared to eMMC, I see the following

fastboot_ error_ failed to identify current slot output from fastboot getvar all : security-patch-level: current-slot:b