No warning if a custom tool dependency is not valid or has an empty path

Scenario:

1. Download both attached files and put them into the same location.
2. Open the "External Tools" page the "Application Settings" dialog.
3. Remove the "perl" tool path if it's set.
4. Import the "custom_with_perl_dependency.xml" tool
   Expected result: the tool was imported, there is a warning sign near the tool icon. A warning notification appears at the right bottom corner of the UGENE window and a message is written to the log:

   The imported custom external tool 'imported_tool_name' depends on the 'launcher_tool' that is not set. Make sure to specify a correct path for it.
   

   Current result: the tool was imported, there is a warning sign near the tool icon. There is NO notification or message in the log.