Skip welcome if there is no TTY (#5414)

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---------

Co-authored-by: a <1@1.1>

tests/test_integrations.py

@@ -1246,6 +1246,7 @@ def test_catching_system_exit():
 
 
 @skip_if_on_windows
+@pytest.mark.flaky(reruns=3, reruns_delay=1)
 def test_catching_exit_signal():
     stdin_cmd = "kill -SIGHUP @(__import__('os').getpid())\n"
     out, err, ret = run_xonsh(

xonsh/main.py

@@ -528,6 +528,7 @@ def main_xonsh(args):
             ignore_sigtstp()
             if (
                 env["XONSH_INTERACTIVE"]
+                and sys.stdin.isatty()  # In case the interactive mode is forced but no tty (input from pipe).
                 and not any(os.path.isfile(i) for i in env["XONSHRC"])
                 and not any(os.path.isdir(i) for i in env["XONSHRC_DIR"])
             ):