tweak AsciiDoc backend

gramps/gui/plug/report/_docreportdialog.py

@@ -260,6 +260,7 @@ class DocReportDialog(ReportDialog):
         """Parse the format frame of the dialog.  Save the user
         selected output format for later use."""
         docgen_plugin = self.format_menu.get_active_plugin()
+        self.basedocname = docgen_plugin.get_basedocname()
         self.format = docgen_plugin.get_basedoc()
         format_name = docgen_plugin.get_extension()
         self.options.handler.set_format_name(format_name)

gramps/plugins/docgen/asciidoc.py

@@ -172,8 +172,7 @@ class AsciiDoc(BaseDoc, TextDoc):
         try:
             self.file = open(self.filename, "w", errors='backslashreplace')
         except Exception as msg:
-            errmsg = "%s\n%s" % (_("Could not create %s") % self.filename, msg)
-            raise ReportError(errmsg)
+            raise ReportError(_("Could not create %s") % self.filename, msg)
 
         self.in_cell = 0
         self.text = ""