How to update & rebuild CV2 on Raspberry Pi

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Hi at all,

before explaining my problem, I feeling really stupid about asking such an "easy" question, but I searched the Internet for about three hours without any result.

I have a running version of OpenCV 3.1.0 installed on my Raspberry Pi (Linux Raspbian, Python 3) since September this year, used: http://www.pyimagesearch.com/2016/04/...

cv2.__version__ says 3.1.0

In 2015 there was a bug according to the fisheye-calibration and in April 2016 a fix was officially committed on GitHub: https://github.com/opencv/opencv/pull...

Now, I want to re-download changed files and rebuild OpenCV to take advantage of the bug-fix (if this is the right way to handle an update). Another question is why I could download a bug-file after there was a fix half a year ago.

As I said, I was seeking for an answer for hours, but "update open cv linux" or "git update rebuild open cv" results in lots of crap.

Thank you all in advance!