Hello all,

The function \scan_align_safe_stop: is deprecated for removal after the
end of 2016. In place of this function, programmers should ensure that
functions testing for example \mode_if_math:TF are protected

Reasoning. \scan_align_safe_stop: was originally introduced in an
attempt to allow fully expandable mode tests at the start of alignment
cells, etc. However, after reviewing the original code the team realised
that this was not a viable approach. The current \scan_align_safe_stop:
is therefore simply a protected version of \prg_do_nothing:. However,
this adds nothing to making the calling function itself protected.
Joseph Wright