twitter/bootstrap — pull request #4135 by Xerkus (2012-07-22 04:45:15+00:00)
Title: allow reuse of makefile

Set BOOTSTRAP_LESS and BOOTSTRAP_RESPONSIVE_LESS variables only if they not already set to allow easily extend bootstrap .less and reuse makefile.

example: https://github.com/Xerkus/CustomTwBootstrap/tree/master