Don't clear cancellable at the beginning and extra cancelled testing

We had to revert our previous fix for #13049 due to other Help related
issues. When there was an error condition when searching or dowloading
the xml help index, the progress widget was not closed and stayed
in the status bar until the Cancel button was clicked.

Fix this by properyly calling `_gimp_help_progress_finish` when tere
is an error condition.

plug-ins/help/gimphelplocale.c

@@ -217,7 +217,7 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
       _gimp_help_progress_start (progress, cancellable,
                                  _("Loading index from '%s'"), name);
 
-      g_clear_object (&cancellable);
+      //g_clear_object (&cancellable);
       g_free (name);
     }
 
@@ -238,6 +238,11 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
       locale_set_error (error,
                         _("Could not load data from '%s': %s"), file);
       g_object_unref (file);
+      if (progress)
+        {
+          _gimp_help_progress_finish (progress);
+          g_clear_object (&cancellable);
+        }
       return FALSE;
     }
 
@@ -249,11 +254,20 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
       GFileInfo *info = g_file_query_info (file,
                                            G_FILE_ATTRIBUTE_STANDARD_SIZE, 0,
                                            cancellable, error);
+      if (g_cancellable_is_cancelled (cancellable))
+        {
+          /* Temporary separation to see if we get cancelled here */
+          g_printerr ("Query operation was cancelled!\n");
+          g_object_unref (info);
+          info = NULL;
+        }
       if (! info)
         {
           locale_set_error (error,
                             _("Could not open '%s' for reading: %s"), file);
           g_object_unref (file);
+          _gimp_help_progress_finish (progress);
+          g_clear_object (&cancellable);
 
           return FALSE;
         }
@@ -265,11 +279,21 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
 
   stream = g_file_read (file, cancellable, error);
 
+  if (g_cancellable_is_cancelled (cancellable))
+    {
+      /* Temporary separation to see if we get cancelled here */
+      g_printerr ("Read operation was cancelled!\n");
+      g_object_unref (stream);
+      stream = NULL;
+    }
   if (! stream)
     {
       locale_set_error (error,
                         _("Could not open '%s' for reading: %s"), file);
       g_object_unref (file);
+      if (progress)
+        _gimp_help_progress_finish (progress);
+      g_clear_object (&cancellable);
 
       return FALSE;
     }
@@ -301,6 +325,7 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
 #endif /* ! PLATFORM_OSX */
   if (progress)
     _gimp_help_progress_finish (progress);
+  g_clear_object (&cancellable);
 
   g_markup_parse_context_free (context);