Editing a Post With an Existing Custom Field Value Containing an HTML Encoded Entity Produces an Unescaped Character Upon Save.

[qweenie]

Editing a Post With an Existing Custom Field Value Containing an HTML Encoded Entity Produces an Unescaped Character Upon Save.

ENV: WP trunk 2.5 revision 7502
Repro: Always
Steps:

1. update a custom field with value of 'lopez & gwatney'
   
2. view post and the source of page shows a valid html escaped entity 'lopez & gwatney'
   
3. edit same post changing category and save
   
4. view post and the source of page shows invalid unescaped character. 'lopez & gwatney'
   

Expected Result:
Source of page to show 'lopez & gwatney' when displaying custom field value

Looks like we moved to using a <textarea /> but are still using attribute_escape() instead of htmlspecialchars()

(In [7506]) Preserve HTML entities in Custom Fields. fixes #6374