Add HOMEBREW_UPDATE_REPORT_ONLY_INSTALLED

[MikeMcQuaid]

This allows reducing the volume of brew update output by only outputting the changes to formulae that you have installed.

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

[reitermarkus]

I thought the problem was that casks are shown even if the version is the same?

[MikeMcQuaid]

@reitermarkus That is a problem but I personally find even being notified about formulae updates that I don't have installed to be annoying.

[Porkepix]

Won't this still report installed casks as updated while those are not either?

[MikeMcQuaid]

@Porkepix I don't understand the question, sorry?

[reitermarkus]

@Porkepix I don't understand the question, sorry?

It will still show installed casks as updated even if their version doesn't change, right?

[MikeMcQuaid]

It will still show installed casks as updated even if their version doesn't change, right?

Correct.

[Porkepix]

Yep, exactly the explanation reitermarkus gave.

[miccal]

@MikeMcQuaid I have not forgotten about this -- I believe that the first step would be to create a variant of formula_versions for Casks, and I have been working on it as best as I can, but it is taking a little while.