Popular plugins feed doesn't validate

[iandunn]

The popular plugins feed (which is fetched by the News dashboard widget in Core) is outputting invalid. Because of that, the News widget isn't showing the plugins.

var_dump( fetch_feed( 'https://wordpress.org/plugins/browse/popular/feed/' ) ):

object(WP_Error)[791]
  public 'errors' => 
    array (size=1)
      'simplepie-error' => 
        array (size=1)
          0 => string 'This XML document is invalid, likely due to invalid characters. XML error: Undeclared entity error at line 11, column 24' (length=120)
  public 'error_data' => 
    array (size=0)
      empty

I'm guessing this broke with the launch of the new directory.

[iandunn]

Possibly related: #624

Related ​https://core.trac.wordpress.org/ticket/40416

[SergeyBiryukov]

Caused by the — entity added in [5213].

2723.patch​ should solve this.

[iandunn]

In 5320:

Plugin Directory: Replace — with — in feeds.

— is not a valid entity in an RSS feed.

Fixes #2723
Props SergeyBiryukov