vim-patch:7.4.284  #748

Problem:    Setting 'langmap' in the modeline can cause trouble.  E.g. mapping
            ":" breaks many commands. (Jens-Wolfhard Schicke-Uffmann)
Solution:   Disallow setting 'langmap' from the modeline.

https://code.google.com/p/vim/source/detail?r=3c35ca9666e88a8024af6dab585b8e79ab295f83