HTML editor help button uses alt tag as the popup window name

With debugging on, editors with help give this error:

The $name of a popup window shouldn't contain spaces - string modified. Read carefully, Write carefully and About the HTML editor changed to Read_carefully,_Write_carefully_and_About_the_HTML_editor

• line 734 of lib/weblib.php: call to debugging()
• line 786 of lib/weblib.php: call to element_to_popup_window()
• line 5812 of lib/weblib.php: call to link_to_popup_window()
• line ? of unknownfile: call to editorhelpbutton()
• line 48 of lib/form/textarea.php: call to call_user_func_array()
• line 1051 of lib/formslib.php: call to MoodleQuickForm_textarea->setHelpButton()
• line 161 of mod/resource/type/text/resource.class.php: call to MoodleQuickForm->setHelpButton()
• line 44 of mod/resource/mod_form.php: call to resource_text->setup_elements()
• line 117 of lib/formslib.php: call to mod_resource_mod_form->definition()
• line 40 of course/moodleform_mod.php: call to moodleform->moodleform()
• line 182 of course/modedit.php: call to moodleform_mod->moodleform_mod()