ValueFlow: Change value to 'Possible' after conditional assignment in inner loop

lib/valueflow.cpp

@@ -1002,10 +1002,13 @@ static bool valueFlowForward(Token * const               startToken,
                 for (it = values.begin(); it != values.end();) {
                     if (it->condition || it->conditional)
                         values.erase(it++);
-                    else
+                    else {
+                        if (it->valueKind == ValueFlow::Value::Known)
+                            it->valueKind = ValueFlow::Value::Possible;
                         ++it;
                     }
                 }
+            }
 
             // stop after conditional noreturn scopes that are executed
             if (isReturn(end)) {

test/testvalueflow.cpp

@@ -1548,6 +1548,24 @@ private:
         ASSERT_EQUALS(9, value.intvalue);
         ASSERT_EQUALS(ValueFlow::Value::ValueKind::Possible, value.valueKind);
 
+        code = "void f() {\n"
+               "  int x = 0;\n"
+               "  for (int i = 0; i < 10; i++) {\n"
+               "    if (cond) {\n"
+               "      x = 1;\n"
+               "      break;\n"
+               "    }\n"
+               "  }\n"
+               "  if (!x) {}\n"  // <- possible value
+               "}";
+        std::list<ValueFlow::Value> values = tokenValues(code, "!");
+        bool possible = false;
+        for (std::list<ValueFlow::Value>::const_iterator it = values.begin(); it != values.end(); ++it) {
+            if (it->valueKind == ValueFlow::Value::Possible)
+                possible = true;
+        }
+        ASSERT_EQUALS(true, possible);
+
         // after condition
         code = "int f(int x) {\n"
                "  if (x == 4) {}\n"