alibaba/tengine — pull request #404 by taoyuanyuan (2014-02-08 13:36:06+00:00)
Title: trim supports variable value (on/off). 

e.g.
set $html_trim "on";
if (Some Condition) { set $html_trim "off" }
trim $html_trim;
trim_js $html_trim;
trim_css $html_trim;