When the `search` plugin is enabled, with the options:

```
# search plugin
# path to the omega cgi program
omega_cgi: /usr/lib/cgi-bin/omega/omega
# use google site search rather than internal xapian index?
google_search: 0
```

Then we see the following error when editing a page from the web browser UI or running `ikiwiki --rebuild`:

```
Error: Exception: Db block overwritten - are there multiple writers?
```

The issue goes away when we disable the 'search' plugin.

We're running ikiwiki version 3.20180228-1.

> Every time?
> I used to see an error (this one, I think) intermittently on OS X, on incremental rebuilds only.
> Haven't seen it in a while, though.
> Maybe something got fixed upstream.
> What OS, and what version of Xapian and Omega?
> (1.4.11 for me.)
> Maybe worth blowing away `.ikiwiki/xapian/`, as described in [[tips/inside_dot_ikiwiki]]?
> 
> --[[schmonz]]