Correct $HOME during llvmcov

Author: palfrey

flake.nix

@@ -297,6 +297,14 @@
           (nightlyCraneLibFor p).cargoLlvmCov (coverageArgs
             // {
               cargoArtifacts = nightlyCargoArtifactsFor p;
+              preConfigurePhases = ["tempHome"];
+              tempHome = ''
+                # Default home at this point is /homeless-shelter, which doesn't exist and so breaks things like
+                # the Mongo downloader
+                echo "HOME was ''${HOME}"
+                export HOME=$(mktemp -d fake-homeXXXX --tmpdir)
+                echo "HOME is now ''${HOME}"
+              '';
               cargoExtraArgs = builtins.concatStringsSep " " [
                 "--all"
                 "--locked"