Conversion from wia with --compression purge to ISO doesn't preserve original wia's date modified

[bilditup1]

First of all thank you for these fascinating and useful tools! Like the title says, when converting from purged wia to iso the date modified field is the date the new iso is created, and doesn't take the date from the wia it is converted from. I'm not sure if this is intentional or unavoidable behavior or not, but by contrast, wia --compression=none preserves the date modified timestamp by default, so I wasn't sure. This is using 3.04a-r8427. In both cases, --psel set to raw, no scrubbing.