Properly report build errors on chrooted stores

When encountering a build error, Nix moves the output paths out of the
chroot into their final location (for “easier debugging of build
failures”). However this was broken for chroot stores as it was moving
it to the _logical_ location, not the _physical_ one.

Fix it by moving to the physical (_real_) location.

Fix NixOS#8395

src/libstore/build/local-derivation-goal.cc

@@ -357,7 +357,7 @@ bool LocalDerivationGoal::cleanupDecideWhetherDiskFull()
         for (auto & [_, status] : initialOutputs) {
             if (!status.known) continue;
             if (buildMode != bmCheck && status.known->isValid()) continue;
-            auto p = worker.store.printStorePath(status.known->path);
+            auto p = worker.store.toRealPath(status.known->path);
             if (pathExists(chrootRootDir + p))
                 renameFile((chrootRootDir + p), p);
         }