It now only checks that each derivation's drvPath attribute evaluates.
Previously it checked everything (via toXML) but that causes
derivations with dubious passthru attribute to fail (see commit
70fee5da112b8a0093d59ac16cdead4d0a72f357).
Now that we don't need to pass "system" arguments anymore, this thing
is *almost* obsolete. (Except for the need to handle assertion
failures, you could just do "nix-instantiate --eval-only ..." on
release.nix.)
derivation evaluate inside the tryEval. This catches cases such as
aufs2-util, which fails due to an assertion in its dependency aufs2.
* Explicitly blacklist "xbursttools" because it gives some
evaluation error in cross-OpenSSL. No idea why, probably due to
some pass-through attribute.
svn path=/nixpkgs/trunk/; revision=23247