Acme_tiny.py perms prob with challenges dir

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no files in challenges other than i test one

a browse to http://foo.u/.well-known/acme-challenge/foo
does display the content of the file foo

<VirtualHost _default_:80>
    ServerName foo.u
    DocumentRoot "/home/acme/challenges"
    <Directory "/home/acme/challenges">
        AllowOverride FileInfo AuthConfig Limit Indexes
        Options Indexes FollowSymLinks MultiViews
        AllowOverride None
        Order allow,deny
        Require all granted
        Allow from all
        </Directory>
    Alias /.well-known/acme-challenge "/home/acme/challenges"
    </VirtualHost>

i believe the problem is indeed perms for write, as the log message is

[Sun Dec 06 14:01:06.684373 2015] [core:error] [pid 759] (13)Permission denied: [client 42.28.0.666:35964] AH00132: file permissions deny server access: /home/acme/challenges/zeiHTeaxu_Uk-QT6-OTcjB6G6p3V_X5DGGh-EtNe11I

but i suspect the apache config more than file perms/owners, but acme user can write to a file in challenges, and a web browser can read that file. so i feel more stupid than usual.