export > $NIX_BUILD_TOP/env-vars
will fail if the name attribute contains a metacharacter
(e.g. "?"):
building path(s) `/nix/store/yk93gk3lc5bslcn5hklnzs0bdkp2r0an-icu-3.8-setBreakType-public.diff?rev=1.1'
/nix/store/gj8ac12mrwinbq7wzzhwfjjs3028a11x-stdenv-linux/setup: line 374: $NIX_BUILD_TOP/env-vars: ambiguous redirect
I guess this only happens if you happen to have an old temporary
build directory for the same derivation in /tmp.
This affects fetchurl in particular.
svn path=/nixpkgs/trunk/; revision=15915
2d0b32453c