Make update script support multiple copies

Bug: 199522401
Test: ./download_exoplayer.py --commit=410ddf458c4daebcf3f997084891c82f2dbd6805
Change-Id: I277f0d43da799fc717bdb2506df0fe2226997839
Merged-In: I277f0d43da799fc717bdb2506df0fe2226997839
(cherry picked from commit 2165cb7eb987107c50d1b576bddaa032fac880b6)
2 files changed