Position of the options does not change when multi select grows in height

[jklapwijk]

Prerequisites

• I have searched for similar issues in both open and closed tickets and cannot find a duplicate
• The issue still exists against the latest master branch of Select2
• This is not a usage question (Those should be directed to the community)
• I have attempted to find the simplest possible steps to reproduce the issue
• I have included a failing test as a pull request (Optional)

Steps to reproduce the issue

1. Go to this jsfiddle: http://jsbin.com/gixemazama/1/edit?html,js,output
2. add option B to the selection

Expected behavior and actual behavior

The input with the selected options is now higher and contains option B, but the option list remains on the same spot, so it is in front of the selected options and therefore the selected option B is not visible.

I was expecting that the option list would be attached to the bottom of the selection list and therefore would move down.

Environment

Browsers

• Google Chrome
• Mozilla Firefox
• Edge

Operating System

• Windows
• Mac OS X
• Linux
• Mobile

Libraries

• jQuery version: 3.2.1
• Select2 version: 4.0.3

Isolating the problem

• This bug happens on the examples page
• The bug happens consistently across all tested browsers
• This bug happens when using Select2 without other plugins
• I can reproduce this bug in a jsbin

[alexweissman]

Confirmed problem, and updated jsbin: http://jsbin.com/nolajupeco/1/edit?html,js,output

[alexweissman]

Actually, just realized that this is a duplicate of #4511 and #4377.