BUG: Fix svn update logic for modified files

The main svn update parsing loop in cmCTestUpdateHandler previously had
a logic error because the variable 'res' was not reset for each
iteration.  For a locally modified file it would report the update info
for the previous non-modified file, or nothing if there was no previous
file.  This fixes the logic by setting variable 'res' in both control
paths for each iteration.  See issue #8168.

Source/CTest/cmCTestUpdateHandler.cxx

@@ -807,6 +807,10 @@ int cmCTestUpdateHandler::ProcessHandler()
           ofs << output << std::endl;
           }
         }
+      else
+        {
+        res = false;
+        }
       if ( res )
         {
         cmCTestLog(this->CTest, DEBUG, output << std::endl);