nix-env failed:
error: while evaluating anonymous function at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/.gc-of-borg-outpaths.nix:44:12, called from undefined position:
while evaluating anonymous function at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/pkgs/top-level/release-lib.nix:121:6, called from /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/lib/attrsets.nix:292:43:
while evaluating 'hydraJob' at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/lib/customisation.nix:157:14, called from /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/pkgs/top-level/release-lib.nix:121:14:
while evaluating the attribute 'drvPath' at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/lib/customisation.nix:174:13:
while evaluating the attribute 'drvPath' at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/lib/customisation.nix:141:13:
while evaluating the attribute 'buildPhase' of the derivation 'msbuild-16.3+xamarinxplat.2019.07.26.14.57' at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/pkgs/stdenv/generic/make-derivation.nix:191:11:
cannot coerce null to a string, at /var/lib/ofborg/checkout/repo/38dca4e3aa6bca43ea96d2fcc04e8229/mr-est/eval-2-shlevy.ewr1.nix.ci/pkgs/development/tools/build-managers/msbuild/default.nix:38:16