failed to compile bootstrap.less

[ftiasch]

running lessc bootstrap.less under /less gave me following error:

at less.Parser.parser.parse.i (/Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/js/lib/less/parser.js:385:31): #grid > .core is undefined (Less::ParseError)
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/parser.rb:61:in `block in to_css'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script/v8_context.rb:90:in `block in do_lock'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script/v8_context.rb:88:in `call'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script/v8_context.rb:88:in `Locker'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script/v8_context.rb:88:in `do_lock'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script/v8_context.rb:60:in `lock'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script/v8_context.rb:30:in `exec'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/java_script.rb:26:in `exec'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/lib/less/parser.rb:61:in `to_css'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/gems/less-2.2.2/bin/lessc:99:in `'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/bin/lessc:19:in `load'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/bin/lessc:19:in `'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/bin/ruby_noexec_wrapper:14:in `eval'
    from /Users/ftiasch/.rvm/gems/ruby-1.9.3-p374/bin/ruby_noexec_wrapper:14:in `'

lessc -v
lessc 1.3.0 (LESS Compiler) [Ruby] 2.2.2

[cvrebert]

Duplicate of #6856 (modulo the Ruby wrapper); please search next time.
Upgrade to less.js v1.3.3.