web view crashes when viewing repo with mq patches

[Greg Ward]

[moving from user list]
>> It seems hg wants to create a .hg/tags.cache inside my repo, but the
>> www-data user who starts the CGI process does not have the right to
>> create a file there.
>
> That seems like a problem. Greg, can you fix this?

Oooops.  Yes, this should be easy enough.  However, I should write a
test too.  So I probably won't finish this until tomorrow.

Greg