Bugfix: rename replaces parent directory (issue #3750) (#3751)

* nemo-file-conflict-dialog.c: check for empty dialog->details->entry

No call to nemo_file_conflict_dialog_get_new_name() would usually be
possible while entry is empty, but can be made to happen, see #3750.

* nemo-file-conflict-dialog.c: hide details->rename_button initially

Ensure the existing attempt to hide details->rename_button is not
undone by the call to gtk_widget_show_all() at the end of the
nemo_file_conflict_dialog_init() function.

Fixes #3750.

Author: jeth-ro

libnemo-private/nemo-file-conflict-dialog.c

@@ -566,6 +566,7 @@ nemo_file_conflict_dialog_init (NemoFileConflictDialog *fcd)
 				       _("Re_name"),
 				       CONFLICT_RESPONSE_RENAME);
 	gtk_widget_hide (details->rename_button);
+	gtk_widget_set_no_show_all(details->rename_button, TRUE);
 
 	details->replace_button =
 		gtk_dialog_add_button (dialog,
@@ -622,6 +623,7 @@ nemo_file_conflict_dialog_class_init (NemoFileConflictDialogClass *klass)
 char *
 nemo_file_conflict_dialog_get_new_name (NemoFileConflictDialog *dialog)
 {
+	g_assert(gtk_entry_get_text_length (GTK_ENTRY (dialog->details->entry)) > 0);
 	return g_strdup (gtk_entry_get_text
 			 (GTK_ENTRY (dialog->details->entry)));
 }