better return text that ret code 127

[jscotka]

It is not clear what: Unexpected server exit code 127. means
ping
Scenarios:
loopback
Connection: Socket(6/AF_INET/SOCK_DGRAM/0)
[3.760 client 5476] socket(AF_INET, SOCK_DGRAM, 0) = 6
[3.765 client 5476] connect(6, <sockaddr_in sin_family=2, sin_port=1025, sin_addr=127.0.0.1>, 16) = 0
[3.776 client 5476] close(6) = 0
Unexpected server exit code 127.

It could be translated to some better string in cases of known ret code like that (killed after timeout, or similar)