fix build-compare support in chroot mode

(fix the place that really matters)

diff --git a/build b/build
index b2a0499..a7f1e37 100755 (executable)
--- a/build
+++ b/build
@@ -1456,7 +1456,7 @@ for SPECFILE in "${SPECFILES[@]}" ; do
        fi
        mount -n -tproc none $BUILD_ROOT/proc || true
        mount -n -tdevpts none $BUILD_ROOT/dev/pts
-       if [ -d "$OLD_PACKAGES" ]; then
+       if [ -d "$OLD_PACKAGES" -a "$OLD_PACKAGES" != "$BUILD_ROOT/.build.oldpackages" ] ; then
           rm -rf "$BUILD_ROOT/.build.oldpackages"
           cp -r $OLD_PACKAGES $BUILD_ROOT/.build.oldpackages
        fi