The gRPC client reconnect code needs to be able to check if a error is temporary so that it can decide if it should attempt to reconnect or just fail and kill the client[1]. By wrapping the error we were receiving in our TLS handshake code we were removing the existing `Temporary` interface on the error. This meant that if a client attempted to reconnect to a server that was in the process of being shutdown, the client would consider that server permanently dead and never retry.
Fix is simple: don't wrap errors that we pass back into the gRPC internals so that they can be properly inspected.
[1]: aefc96d792/clientconn.go (L783)
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