Index: modules/http/http_protocol.c
===================================================================
--- modules/http/http_protocol.c	(revision 831907)
+++ modules/http/http_protocol.c	(working copy)
@@ -174,6 +174,17 @@
                               "close");
     const char *conn = apr_table_get(r->headers_in, "Connection");
 
+    /* PR47087: If the client sent Expect: 100 and we didn't reply
+     * with the same, there may be more data we screw up.
+     * Closing the connection fixes that.  Furthermore, when we're
+     * sending an error or redirection, closing it is likely to be
+     * the most efficient thing to do too.
+     *
+     * Yes this logic could go in the big if, but let's KISS instead.
+     */
+    if (r->expecting_100 && (r->status != HTTP_CONTINUE)) {
+        r->connection->keepalive = AP_CONN_CLOSE;
+    }
     /* The following convoluted conditional determines whether or not
      * the current connection should remain persistent after this response
      * (a.k.a. HTTP Keep-Alive) and whether or not the output message