Test: Ran "source build/envsetup.sh && source build/rbesetup.sh", then ran "use_rbe m" and that worked. Bug: b/150705712 Change-Id: I2d49fefbc1121f0d9c4e652396753b096e555a79 Merged-In: I2413a3648e9b2ff680cab6fededc07bbdd43378f