Merge branch 'PHP-7.4'

* PHP-7.4:
  Fix #54298: Using empty additional_headers adding extraneous CRLF

Author: cmb69

ext/standard/mail.c

@@ -333,7 +333,7 @@ PHP_FUNCTION(mail)
 		extra_cmd = php_escape_shell_cmd(ZSTR_VAL(extra_cmd));
 	}
 
-	if (php_mail(to_r, subject_r, message, headers_str ? ZSTR_VAL(headers_str) : NULL, extra_cmd ? ZSTR_VAL(extra_cmd) : NULL)) {
+	if (php_mail(to_r, subject_r, message, headers_str && ZSTR_LEN(headers_str) ? ZSTR_VAL(headers_str) : NULL, extra_cmd ? ZSTR_VAL(extra_cmd) : NULL)) {
 		RETVAL_TRUE;
 	} else {
 		RETVAL_FALSE;

ext/standard/tests/mail/bug54298.phpt

@@ -0,0 +1,24 @@
+--TEST--
+Bug #54298 (Using empty additional_headers adding extraneous CRLF)
+--INI--
+sendmail_path=tee bug54298.eml >/dev/null
+mail.add_x_header = Off
+--SKIPIF--
+<?php
+if (PHP_OS_FAMILY === 'Windows') die("skip Won't run on Windows");
+?>
+--FILE--
+<?php
+var_dump(mail('[email protected]', 'testsubj', 'Body part', ''));
+echo file_get_contents('bug54298.eml');
+?>
+--EXPECT--
+bool(true)
+To: [email protected]
+Subject: testsubj
+
+Body part
+--CLEAN--
+<?php
+unlink('bug54298.eml');
+?>