Exclude Delay in course renewal in Drip timer for drip Starting Points

A drip with a starting point is different from a standard drip course.

In a standard drip course the drip duration applies between each successive unit. For section drip, the drip duration would be between each successive section.

So the time calculation happens from the Start of the unit before the current unit.

But this is not useful when you want to keep students at the same unit level. As anyone who joins late will always remain late and never catch up with the current unit in the curriculum. 

For this purpose we created a starting point drip.

For Drip timer calculation we use the starting point instead of start of previous unit. So this means

Example : 

A yoga class starting on 1stJanuary with Drip 1 day per unit.

A person joining on 7th day will get access to all 7 units at once and the drip timer would start only for unit 8, just like everyone else who joined the course.

However, there was a bug that when this is enabled,  a user whose course expires, can rejoin at a later date and get access to all the units in the course.

For this purpose we created this  tip :  https://gist.github.com/MrVibe/6078fcd3ebd5215c0ee90112add7ad9e