Ensure that quantities are converted to Magnitude instances if needed.

[mhvk]

This fixes the second issue raised in #5178, allowing quantities to be converted to magnitudes as needed.

In current master:

(10.*u.STmag).physical.to(u.STmag)
<Quantity 10.0 mag(ST)>

With this PR:

(10.*u.STmag).physical.to(u.STmag)
<Magnitude 10.0 mag(ST)>

[pllim]

Thanks! Is the .physical part compulsory? So, I cannot simply do (10.*u.STmag).to(u.STmag)?

[mhvk]

The .physical is just to ensure one triggers the error, which needs conversion from a physical quantity to a magnitude; (10.*u.STmag).to(u.STmag) worked fine as it was.

[mhvk]

@adrn - would you be able to have a look? I think this change is fine, but a second look is always good...

[adrn]

@mhvk looks fine to me!

[mhvk]

@adrn - thanks for the quick review! Merged...

[astrobot]

@mhvk - thanks for merging this! However, I noticed the following issue with this pull request:

• Changelog entry not present (or pull request number missing) and neither the Affects-dev nor the no-changelog-entry-needed label are set

Would it be possible to fix this? Thanks!

This is an experimental bot being written by @astrofrog - let me know if the message above is incorrect!

[mhvk]

See #5187 for the missing changelog entry.

[pllim]

I can confirmed that this fixed my problem. Thanks!!!