user_email_used error string is not used anywhere?

[pavelevap]

During localization I found a string that I could not see anywhere. I could reproduce it only in one situation and that does not make sense (string should not be displayed in this case). Maybe we could remove the whole string and related logic because is obsolete and never used? See attached patch.

Or if I am missing something, this string should be at least improved a little (capital letter).

Introduced in ​mu:825. Doesn't seem to be used or displayed anywhere.

show_user_form() only displays get_error_message('user_email'), which is set in the next block
http://core.trac.wordpress.org/browser/tags/3.4.2/wp-includes/ms-functions.php#L507
http://core.trac.wordpress.org/browser/tags/3.4.2/wp-signup.php#L134

patch looks good.

Refreshed to remove an empty line

Found one more piece of dead code:
http://core.trac.wordpress.org/browser/tags/3.5.1/wp-signup.php#L139

We don't use 'generic' error code anywhere in core. If a plugin wants to display a custom error message there, signup_extra_fields action can be used for that.

Replying to SergeyBiryukov:

Found one more piece of dead code

Introduced in ​mu:543 along with the file itself.

Replying to SergeyBiryukov:

We don't use 'generic' error code anywhere in core.

Some plugins and one theme appear to be using it:

• ​http://plugins.trac.wordpress.org/browser/retina-post/trunk/wp-retina.php?rev=525085#L151
• ​http://plugins.trac.wordpress.org/browser/retina-post-multisite/trunk/wp-retina.php?rev=462990#L228
• ​http://plugins.trac.wordpress.org/browser/bwp-recaptcha/trunk/includes/class-bwp-recaptcha.php?rev=443096#L652
• ​http://plugins.trac.wordpress.org/browser/better-wordpress-recaptcha-for-cloudflare-sites/trunk/includes/class-bwp-recaptcha.php?rev=542891#L652
• ​https://github.com/logicmd/mystique/blob/master/mystique/templates/page-lost-pw.php#L61

In 23412:

Remove unused error string. props pavelevap. fixes #22107.