dynamically remove line separator in bytedump.sh

etc/bytedump.sh

@@ -7,23 +7,28 @@ coqtop -q -quiet $COQFLAGS 2>/dev/null << EOF
 Require bedrock2.PrintListByte ${1%.*}.
 Local Set Printing Width 2147483647.
 Goal True.
-  idtac "COQTOP_CRAP_ENDS_HERE".
+  idtac "COQBUG(15373)".
+  idtac "LINE_SEPARATOR_LOTTERY".
   PrintListByte.print_list_byte ${1}.
 Abort.
 EOF
-} | python3 -c '
-import os, sys
-needle = b"\nCOQTOP_CRAP_ENDS_HERE\n"
-waiting_on_coqbug_15373 = True
+} | python3 -c '#  strip header, detect \r\n or \n, convert to \n, strip last \n
+import os, sys # os.linesep is \n on cygwin but \r\n in cygwin coq on github ci
+b = b""
+while not b.endswith(b"COQBUG(15373)"):
+	r = os.read(0, 1); b += r
+	if not r: print(f"{b!r}"); sys.exit(4)
+b = b""
+while not b.endswith(b"LINE_SEPARATOR_LOTTERY"):
+	r = os.read(0, 1); b += r
+	if not r: print(f"{b!r}"); sys.exit(3)
+linesep = b[:-len(b"LINE_SEPARATOR_LOTTERY")]
+os.read(0, len(linesep)) == linesep or sys.exit(2)
 b = b""
 while True:
-	r = os.read(0, 1)
-	if not r:
-		sys.exit(waiting_on_coqbug_15373 + 2*(not b.endswith(b"\n")))
-	b = b[-(len(needle)-len(r)):] + r
-	if b == needle:
-		waiting_on_coqbug_15373 = 0
-		b = b""
-	if not waiting_on_coqbug_15373:
-		os.write(1, b[-2:-1])
+	r = os.read(0, 1); b += r
+	if not r: sys.exit(not b.endswith(b"\n"))
+	if b == linesep: b = b"\n"
+	os.write(1, b[-2:-1])
+	b = b[-1:]
 '