[PATCH] Fix ctrl-c not working after process substitution

[Eric Freese <ericdfreese@gmail.com>]

This is a potential fix for the ctrl-c problem reported in message 43148

You can reproduce the bug by running `zsh -f`, sourcing the following
.zshrc, and (at the prompt) pressing ^T and then ^C:

    foo-request() {
      exec {FD}< <(echo foo)
      zle -F $FD foo-response
    }

    foo-response() {
      zle -F $1
    }

    zle -N foo-request
    bindkey ^T foo-request

After pressing ^T, ^C doesn't reset the prompt.

I think this is because the forked <(echo foo) process calls
entersubsh() without ESUB_ASYNC flag and so is set as the terminal's
controlling process. My hypothesis is that the original process is never
reset as the terminal's controlling process and thus the SIGINT signals
are no longer sent to the original process.

Adding ESUB_ASYNC flag to the entersubsh() call fixes the issue. I'm not
sure though if there are some cases where we don't want to add the flag
(e.g. when nullexec is 0)?
---
 Src/exec.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Src/exec.c b/Src/exec.c
index 79ef83c1e..6ac852112 100644
--- a/Src/exec.c
+++ b/Src/exec.c
@@ -4984,7 +4984,7 @@ getpipe(char *cmd, int nullexec)
 	procsubstpid = pid;
 	return pipes[!out];
     }
-    entersubsh(ESUB_PGRP, NULL);
+    entersubsh(ESUB_ASYNC|ESUB_PGRP, NULL);
     redup(pipes[out], out);
     closem(FDT_UNUSED, 0);	/* this closes pipes[!out] as well */
     cmdpush(CS_CMDSUBST);
-- 
2.19.0