patch 8.0.0096
Problem: When the input or output is not a tty Vim appears to hang.
Solution: Add the --ttyfail argument. Also add the "ttyin" and "ttyout"
features to be able to check in Vim script.
diff --git a/src/globals.h b/src/globals.h
index c15e4f9..0b6abb0 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -643,6 +643,8 @@
EXTERN int really_exiting INIT(= FALSE);
/* TRUE when we are sure to exit, e.g., after
* a deadly signal */
+EXTERN int stdout_isatty INIT(= TRUE); /* is stdout a terminal? */
+
#if defined(FEAT_AUTOCHDIR)
EXTERN int test_autochdir INIT(= FALSE);
#endif