[Nix-dev] error: setting synchronous mode: unable to open database file

[Mathijs Kwik]

Hi all,

I'm trying to turn my bash scripts for generating my channel nars and
nixexprs.tar.bz2 into nix expressions.
I have a simple shell script that and generates an expression for my
git sources, with a rev and sha256 for it.
Then I import that (sources) expression into a channel-builder
expression, which has derivations like a source-dir and
nixexprs.tar.bz2.
This works fine.
As a next step, I want to build a bunch of dervations (that I consider
part of my channel) using the new sources, and as a last step I want a
derivation that calls nix-push to generate .nar files.

However, the build-derivations-using-the-new-sources derivation gets
me into some trouble.
In it, I modify NIX_PATH and want to call nix-build so it uses the new sources.
But that fails with "error: setting synchronous mode: unable to open
database file".

I have a feeling nix isn't (yet) meant to be called inside nix, but
perhaps the error is caused by something different.
Any suggestions?

Thanks,
Mathijs