SirVer/ultisnips — pull request #387 by ggriffiniii (2014-10-08 00:36:37+00:00)
Title: Use shiftwidth() where available. This allows UltiSnips to work properly...

... when

shiftwidth is zero. Per ":help shiftwidth":

shiftwidth() shiftwidth()
Returns the effective value of 'shiftwidth'. This is the
'shiftwidth' value unless it is zero, in which case it is the
'tabstop' value. To be backwards compatible in indent
plugins, use this:
if exists('*shiftwidth')
func s:sw()
return shiftwidth()
endfunc
else
func s:sw()
return &sw
endfunc
endif
And then use s:sw() instead of &sw.