Fatal error: Cannot redeclare class pear

I was getting this fatal error:

Cannot redeclare class pear in .../sites/default/modules/backup_migrate_files/includes/destinations.filesource.inc on line 166

This patch fixed it.

The fatal error first manifested itself with a WSOD and an error 502 response from the the nginx reverse proxy. Its detailed log reported “upstream prematurely closed connection while reading response header from upstream”