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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@33554 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

io.c

@@ -192,6 +192,7 @@ rb_cloexec_open(const char *pathname, int flags, mode_t mode)
 {
     int ret;
 #ifdef O_CLOEXEC
+    /* O_CLOEXEC is available since Linux 2.6.23.  Linux 2.6.18 silently ignore it. */
     flags |= O_CLOEXEC;
 #endif
     ret = open(pathname, flags, mode);