common sense "and" == boolean logic "or"

doc/sphinx/reference/vcl_var.rst

@@ -728,7 +728,7 @@ beresp.do_stream
 	have been sent to the client may get freed early, depending
 	on the storage engine used.
 
-	This variable has no effect if do_esi is true and when the
+	This variable has no effect if do_esi is true or when the
 	response body is empty.
 
 beresp.do_gzip