From c851be6802b221ca174802adbd43d764d540a5d0 Mon Sep 17 00:00:00 2001
From: Philip Taron <philip.taron@gmail.com>
Date: Tue, 6 Oct 2026 11:13:43 -0700
Subject: [PATCH] vmTools.runInLinuxVM: do not run postHook on the host

Since 26eba25577388 ("runInLinuxVM: re-add sourcing of stdenv &
.attrs.sh"), the host side of runInLinuxVM sources $stdenv/setup so that
preVM can use $out. That also runs postHook on the host, but postHook is
meant for the build inside the VM. runInLinuxImage sets PATH to the
guest's /usr/bin:/bin in postHook, so releaseTools.debBuild's
propagateImageName then failed on the host with
"mkdir: command not found".

Fixes #433008

Assisted-by: Claude Code (claude-opus-5-5)
---
 pkgs/build-support/vm/default.nix | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pkgs/build-support/vm/default.nix b/pkgs/build-support/vm/default.nix
index 82c61ba8462d..0a29ec630beb 100644
--- a/pkgs/build-support/vm/default.nix
+++ b/pkgs/build-support/vm/default.nix
@@ -293,6 +293,10 @@ let
         ${coreutils}/bin/cp $NIX_ATTRS_JSON_FILE $NIX_ATTRS_SH_FILE xchg
         source "$NIX_ATTRS_SH_FILE"
       fi
+      # The setup script is sourced here only so that `preVM` sees `$out` and
+      # friends. `postHook` belongs to the build inside the VM, where it may
+      # rely on the guest's tools (see `runInLinuxImage`), so skip it here.
+      postHook=
       source $stdenv/setup
 
       eval "$preVM"