Concurrent edit course and its layout

2018-01-02 14:36:34,516 [ajp-nio2-8021-exec-2] ERROR AssertException - OLAT::ERROR ^%^ N1-E21 ^%^ org.olat.core.logging 

https://lms.xyz.de/auth/RepositoryEntry/1937375232/CourseNode/96951079275676
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Safari/537.36
**RedScreen** There is already an edit session open for this course: 96829428354868

<dispatchinfo>
	<componentinfo>
		<compname>ffo_main_null</compname>
		<compclass>org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.control.Event</class&gt;
			<command>validation ok</command>
			<tostring>com:validation ok,org.olat.core.gui.control.Event@d62b3f02</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.course.config.ui.courselayout.CourseLayoutGeneratorController</controllername>
		<controllername>org.olat.course.run.CourseRuntimeController</controllername>
		<controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername>
	</controllerinfo>
</dispatchinfo>

>>> stack of 1.cause::org.olat.core.logging.AssertException: There is already an edit session open for this course: 96829428354868
-> at org.olat.course.CourseFactory.openCourseEditSession(CourseFactory.java:980)
   at org.olat.course.config.ui.courselayout.CourseLayoutGeneratorController.formOK(CourseLayoutGeneratorController.java:377)
   at org.olat.core.gui.components.form.flexible.impl.FormBasicController.event(FormBasicController.java:380)
   at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:202)
   at org.olat.core.gui.components.AbstractComponent$1.run(AbstractComponent.java:240)
   at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
   at org.olat.core.gui.components.AbstractComponent.fireEvent(AbstractComponent.java:238)
   at org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer.fireValidation(FormWrapperContainer.java:122)
   at org.olat.core.gui.components.form.flexible.impl.Form.submit(Form.java:479)
   at org.olat.core.gui.components.form.flexible.impl.Form.submit(Form.java:451)
   at org.olat.core.gui.components.form.flexible.impl.elements.FormSubmit.dispatchFormRequest(FormSubmit.java:77)
>>> stack of 2.cause::java.lang.Exception: assertionstackgenerator
-> at org.olat.core.logging.AssertException.<init>(AssertException.java:53)
   at org.olat.course.CourseFactory.openCourseEditSession(CourseFactory.java:980)
   at org.olat.course.config.ui.courselayout.CourseLayoutGeneratorController.formOK(CourseLayoutGeneratorController.java:377)
   at org.olat.core.gui.components.form.flexible.impl.FormBasicController.event(FormBasicController.java:380)
   at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:202)
   at org.olat.core.gui.components.AbstractComponent$1.run(AbstractComponent.java:240)
   at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
   at org.olat.core.gui.components.AbstractComponent.fireEvent(AbstractComponent.java:238)
   at org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer.fireValidation(FormWrapperContainer.java:122)
   at org.olat.core.gui.components.form.flexible.impl.Form.submit(Form.java:479)
   at org.olat.core.gui.components.form.flexible.impl.Form.submit(Form.java:451)