revdial: remove redundant error return condition
revdial: remove redundant error return condition

Change-Id: Ic5e32b36d1b0dfd4c2524ed5b3aa0a3eef3b2e18
Reviewed-on: https://go-review.googlesource.com/c/build/+/111265
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/build,golang/build,golang/build,golang/build