Use wp_specialchars_decode() in the upgrade debugging email subject, same as the production email.

props markoheijnen.
fixes #26471.

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Copy edits to the About page:

- Open Sans is Open Source, so it can't meet Open Source
- 'icons and graphics' is redundant
- Let's not overuse 'beautiful'
- Choose > pick so we don't use 'choose' twice in the same line

See #26387.


Built from https://develop.svn.wordpress.org/trunk@26763


git-svn-id: http://core.svn.wordpress.org/trunk@26651 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Use &nbsp; instead of &#160; as it's more familiar to translators.

See #26387, [26760].

Built from https://develop.svn.wordpress.org/trunk@26764


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Themes: Ensure the image returns a width before checking that it is less than 300px.

see #26459.

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git-svn-id: http://core.svn.wordpress.org/trunk@26653 1a063a9b-81f0-0310-95a4-ce76da25c4cd