changelog: refuse to add revisions with empty usernames
An empty username or a username with a "\n" will make the revision
text contain two "\n\n" sequences -> corrupt repository.
The problem is that changelog.read expects to find exactly one "\n\n"
separator and thus cannot unpack the revision.
200 Script output follows
content-type: text/plain
content-length: 157
content-disposition: inline; filename="some \"text\".txt"
This is just some random text
that will go inside the file and take a few lines.
It is very boring to read, but computers don't
care about things like that.
host - - [date] "GET /?f=a23bf1310f6e;file=sub/some%20%22text%22.txt;style=raw HTTP/1.1" 200 -