line continuation error

[szarski]

When I break a line in any sourced file, like so:

function Abc(a,b,c)
endf

call Abc(1,2,
      \3)

vimspec raises an error:

"TestOutput"  --No lines in buffer--
Error detected while processing /Volumes/workspace/buftabs/test/config_test.vim:
line   44:
E116: Invalid arguments for function Abc
line   45:
E10: \ should be followed by /, ? or &
"vimspec.output" 
"vimspec.output" [New File] 36 lines, 1149 characters written

However, when I use one line everything works fine:

function Abc(a,b,c)
endf

call Abc(1,2,3)

The same code works fine in my plugin and seems to be correct accorging to vim specification (:help line-continuation)