preserve ORIG_BUILD_DIR during the build process

using the apt buildpack in combination with the multi buildpack exports some
paths out of ORIG_BUILD_DIR. By copying instead of moving this should allow
building of python modules that have dependancies on any packages installed
into ORIG_BUILD_DIR.

bin/compile

@@ -83,7 +83,7 @@ if [[ ! "$DOCKER_BUILD" ]]; then
 
   # Copy Application code in.
   bpwatch start appdir_stage
-    deep-mv $BUILD_DIR $APP_DIR
+    deep-cp $BUILD_DIR $APP_DIR
   bpwatch stop appdir_stage
 fi
 
@@ -218,6 +218,7 @@ bpwatch stop dump_cache
 if [[ ! "$DOCKER_BUILD" ]]; then
 
   bpwatch start appdir_commit
+    deep-rm $ORIG_BUILD_DIR
     deep-mv $BUILD_DIR $ORIG_BUILD_DIR
   bpwatch stop appdir_commit