- adapted from https://github.com/nathanchance/AnyKernel2/commit/3dfba3dcabff3cf1f859276e1851ae35891d8801 - works around odd behaviors in TWRP on system-as-root devices, but retains working fallback using /system/system/build.prop if getprop also fails - simplify unmount_all stderr redirection Please see the above linked commit for further details. Thanks to nathanchance for reporting, the device-specific workaround, and much testing