always rm /.build, could be leftover from lxc build

diff --git a/build b/build
index f397668..56047fc 100755 (executable)
--- a/build
+++ b/build
@@ -551,6 +551,7 @@ mkdir_build_root()
     fi
 
     rm -rf "$BUILD_ROOT"/.build.packages
+    rm -rf "$BUILD_ROOT"/.build
 }
 
 linux64()