texinfo.tex - part header in long table of contents

[arnold]

Hi.

Using texinfo.tex 2017-06-04.19, the part header in a table of
contents can come out at the bottom of a page. It'd be better if
it came out at the top of the next page.  To reproduce:

        git clone git://git.savannah.gnu.org/gawk.git
        cd gawk
        ./bootstrap.sh && ./configure && make -j
        cd doc ; make gawk.pdf

Examine page vii of the table of contents and you'll see that the

        Part II: Problem Solving with awk

is at the bottom of the page. It'd look better at the top of
the next page.

Thanks!

Arnold