Simpletest test throws exceptions when Drupal is installed with prefixed table names.
Table names are prefixed in form of drupal_base instead of base.

WD php: PDOException: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'base.language' in 'field list': SELECT base.vid AS vid, base.name AS name, base.machine_name AS             [error]
machine_name, base.description AS description, base.hierarchy AS hierarchy, base.module AS module, base.weight AS weight, base.language AS language, base.i18n_mode AS i18n_mode
FROM
{taxonomy_vocabulary} base
ORDER BY base.weight ASC, base.name ASC; Array
(
)
 in DrupalDefaultEntityController->load() (line 196 of /***/includes/entity.inc).
Drush command terminated abnormally due to an unrecoverable error.                                                                                                                        [error]
Output from failed command :                                                                                                                                                              [error]
 PDOException: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'base.language' in 'field list': SELECT base.vid AS vid, base.name AS name, base.machine_name AS
machine_name, base.description AS description, base.hierarchy AS hierarchy, base.module AS module, base.weight AS weight, base.language AS language, base.i18n_mode AS i18n_mode
FROM
{taxonomy_vocabulary} base
ORDER BY base.weight ASC, base.name ASC; Array
(
)
 in DrupalDefaultEntityController->load() (line 196 of /***/includes/entity.inc).

WD node: EntityMetadataWrapperException: Unknown data property og_membership. in EntityStructureWrapper->getPropertyInfo() (line 339 of                                                   [error]
/***/sites/all/modules/contrib/entity/includes/entity.wrapper.inc).
WD node: EntityMetadataWrapperException: Unknown data property og_membership. in EntityStructureWrapper->getPropertyInfo() (line 339 of                                                   [error]
/***/sites/all/modules/contrib/entity/includes/entity.wrapper.inc).
Organic groups Subgroups permissions inheritance 26 passes, 0 fails, 8 exceptions, and 4 debug messages                                                                                   [error]

( results of running Simpletest test via drush --test-run --all )
Drupal 7.12