tree a6e851894fa464d499a21fe8a9b5f0c758490597
parent ec552f691de57a3937cb2c62abfb8f5e6ad9a535
author Joe Tsai <joetsai@digital-static.net> 1582230517 -0800
committer Joe Tsai <thebrokentoaster@gmail.com> 1582658015 +0000

proto: allow nil with Clone

The v1 behavior of Clone returned nil as is.
Replicate this behavior in v2 for easier migration.

Change-Id: I79d93f15dd9913604027e31e5d9ff309e0c2da61
Reviewed-on: https://go-review.googlesource.com/c/protobuf/+/220437
Reviewed-by: Damien Neil <dneil@google.com>