search form's input box classes breaks autocomplete

To Recreate:
* Install Module
* Select 'Custom autocomplete widget' as 'Autocomplete widget to use'.
* Log-out (anonymous user)
* Try and use auto complete search form on your site

For me the above results in the autocomplete functionality not working. The CSS for authenticated users is as follows
<input type="text" class="form-text apachesolr-autocomplete unprocessed form-autocomplete" title="Enter the terms you wish to search for." value="" size="15" id="edit-search-theme-form-1" name="search_theme_form" maxlength="128" autocomplete="off">

and for anonymous users

<input type="text" class="form-textapachesolr-autocomplete unprocessed" title="Enter the terms you wish to search for." value="" size="15" id="edit-search-theme-form-1" name="search_theme_form" maxlength="128">

With the problem being that 'form-textapachesolr-autocomplete' should be 'form-text apachesolr-autocomplete'

Removing the space from line 71 in apachesolr_autocomplete.module seems to fix

$element['#attributes']['class'] .= ' apachesolr-autocomplete unprocessed';
$element['#attributes']['class'] .= 'apachesolr-autocomplete unprocessed';

but the original code with a space looks right.

Any ideas?