pkt-line: replace "stateless separator" with "response end"

In 0181b600a6 (pkt-line: define PACKET_READ_RESPONSE_END, 2020-05-19),
the Response End packet was defined for Git's network protocol. When the
patch was sent, it included an oversight where the error messages
referenced "stateless separator", the work-in-progress name, over
"response end", the final name chosen.

Correct these error messages by having them correctly reference
a "response end" packet.

Signed-off-by: Denton Liu <liu.denton@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/pkt-line.c b/pkt-line.c
index 8f9bc68..4f0264b 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -103,7 +103,7 @@
 {
 	packet_trace("0002", 4, 1);
 	if (write_in_full(fd, "0002", 4) < 0)
-		die_errno(_("unable to write stateless separator packet"));
+		die_errno(_("unable to write response end packet"));
 }
 
 int packet_flush_gently(int fd)
diff --git a/remote-curl.c b/remote-curl.c
index 75532a8..3c6eceb 100644
--- a/remote-curl.c
+++ b/remote-curl.c
@@ -602,7 +602,7 @@
 			memcpy(buf - 4, "0000", 4);
 			break;
 		case PACKET_READ_RESPONSE_END:
-			die(_("remote server sent stateless separator"));
+			die(_("remote server sent unexpected response end packet"));
 		}
 	}
 
diff --git a/serve.c b/serve.c
index c046926..4bf5e9b 100644
--- a/serve.c
+++ b/serve.c
@@ -218,7 +218,7 @@
 			state = PROCESS_REQUEST_DONE;
 			break;
 		case PACKET_READ_RESPONSE_END:
-			BUG("unexpected stateless separator packet");
+			BUG("unexpected response end packet");
 		}
 	}