Don't unload project out from under someone else.

(Can only currently happen if you import settings from the current
project, but will happen in even more cases once we do MDI.)

Possibly Sentry KICAD-169.

eeschema/dialogs/dialog_schematic_setup.cpp

@@ -154,8 +154,13 @@ void DIALOG_SCHEMATIC_SETUP::onAuxiliaryAction( wxCommandEvent& event )
         return;
 
     wxFileName projectFn( importDlg.GetFilePath() );
+    bool       alreadyLoaded = false;
 
-    if( !m_frame->GetSettingsManager()->LoadProject( projectFn.GetFullPath(), false ) )
+    if( m_frame->GetSettingsManager()->GetProject( projectFn.GetFullPath() ) )
+    {
+        alreadyLoaded = true;
+    }
+    else if( !m_frame->GetSettingsManager()->LoadProject( projectFn.GetFullPath(), false ) )
     {
         wxString msg = wxString::Format( _( "Error importing settings from project:\n"
                                             "Project file %s could not be loaded." ),
@@ -203,5 +208,6 @@ void DIALOG_SCHEMATIC_SETUP::onAuxiliaryAction( wxCommandEvent& event )
                 ->ImportSettingsFrom( file.m_NetSettings );
     }
 
-    m_frame->GetSettingsManager()->UnloadProject( otherPrj, false );
+    if( !alreadyLoaded )
+        m_frame->GetSettingsManager()->UnloadProject( otherPrj, false );
 }