Filter build-chroot-dirs entries that conflict with derivation outputs

Fixes https://github.com/NixOS/nixpkgs/issues/9504.

Note that this means we may have a non-functional /bin/sh in the
chroot while rebuilding Bash or one of its dependencies. Ideally those
packages don't rely on /bin/sh though.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index 0b0064704..c1163e63d 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -1998,13 +1998,13 @@ void DerivationGoal::startBuilder()
             }
         }
 
-        /* If we're repairing or checking, it's possible that we're
+        /* If we're repairing, checking or rebuilding part of a
+           multiple-outputs derivation, it's possible that we're
            rebuilding a path that is in settings.dirsInChroot
            (typically the dependencies of /bin/sh).  Throw them
            out. */
-        if (buildMode != bmNormal)
-            for (auto & i : drv->outputs)
-                dirsInChroot.erase(i.second.path);
+        for (auto & i : drv->outputs)
+            dirsInChroot.erase(i.second.path);
 
 #elif SANDBOX_ENABLED
         /* We don't really have any parent prep work to do (yet?)