prevent local configuration breaking builds

* We use a lot of tools and the user’s configuration may interfere.
* Prevents anything that builds do from breaking the user’s own config and system

Author: mxcl

libexec/stage.ts

@@ -59,9 +59,13 @@ const text = undent`
   set -x
   cd "${srcdir}"
 
+  export HOME="${srcdir}/xyz.tea.home"
   export SRCROOT="${srcdir}"
+  export PREFIX=${flags.prefix}
   ${expand(env)}
 
+  mkdir "$HOME"
+
   export PATH=${brewkit}:"$PATH"
 
   ${pantry_sh}