No access to admin after latest Grav/Admin update

@rkhuster, I'm on Debian 8 with Apache.
@christian_a, Try to run the commands as the www-user:

sudo -u www-data bin/gpm (...)
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Can we move this to the issue tracker: https://github.com/getgrav/grav-plugin-admin/issues/939#issuecomment-273940443

It's not specifically an admin issue, but as there is an open issue there....

Fixed on GPM server side, more info: https://github.com/getgrav/grav/issues/1267#issuecomment-274295364

I finally fixed it by uncommenting RewriteBase in my htaccess. Not clear why this changed after the update but all working now.