Grunt build ends with success even though building failed.

[Reinmar]

I don't have JSDuck installed and I guess that building must have failed but I got:

Reading sample directory /www/ckeditor-sdk/samples
Validating links in samples and index
Parsing categories.
Copying guides
Building documentation.
127

Done, without errors.

The "127" logged after "Building documentation" seems to indicate that some error happened.