bugs found in staging

[pameyer]

Mostly ansible / system config so far.

• disable lighttpd ipv6
• iptables

[pameyer]

Courtesy of @dmurphy's testing:

• presence of files.sha is a subdirectory leads to undefined behavior (in this case the DCM<->DV interactions worked as expected)

[pameyer]

Courtesy of @kcondon's testing:

• presence of files.sha in the dataset already leads to reporting a validation failure.