Pensieve header: A bug in how Mathematica saves subsuperscript boxes.

Dear Mathematica People,

There is a bug around how Mathematica 11.0 saves Subsuperscripts in automatically-generated .m files. For example, I have an initialization cell containing:

f[k_]:=a (Subscript[u, k]^2);

When I evaluate f[k], I get:

a (Subscript[u, k]^2)

But if I save the notebook and read the resulting .m file, I get:

a

and the subsupercript part is dropped. 

See a PDF printout of a complete notebook at http://drorbn.net/AcademicPensieve/Projects/Mathematica/nb/SubsuperscriptBug.pdf, and the notebook itself at http://drorbn.net/AcademicPensieve/Projects/Mathematica/SubsuperscriptBug.nb.

Sincerely,

Dror Bar-Natan.

f[k_]:=a (Subscript[u, k]^2);
g[k_]:=a ((Subscript[u, k])^2);
h[k_]:=a *(Subscript[u, k]^2);

{f[k],g[k],h[k]}

SetDirectory["C:\\drorbn\\AcademicPensieve\\Projects\\Mathematica"]
<< SubsuperscriptBug.m

{f[k],g[k],h[k]}