QbsProjectManager: 'Reparse Qbs' disabled after failed parsing

Steps to reproduce:

• start Creator with enabled QbsProjectManager plugin
• open a corrupt qbs file
• after having failed check context menu entry 'Reparse Qbs' on the projects node (if enabled invoke it)
• fix the issue outside of Creator
• switch back to Creator (without clicking into the editor of Creator - focus must be still the project node)
• check the context menu entry again

Current result:

• 'Reparse Qbs' is disabled

Expected result:

• 'Reparse Qbs' is re-enabled as soon the parsing has been done

Note: If you click into the editor and back onto the navigator or if you click on another node and back to the project node the 'Reparse Qbs' entry is re-enabled.