Fix revert pruner modifying function flows wrong

docs/control-structures.rst

@@ -44,6 +44,7 @@ this nonsensical example::
     // SPDX-License-Identifier: GPL-3.0
     pragma solidity >=0.4.22 <0.9.0;
 
+    // This will report a warning
     contract C {
         function g(uint a) public pure returns (uint ret) { return a + f(); }
         function f() internal pure returns (uint ret) { return g(7) + f(); }