bogus "Negative repeat count does nothing" warnings on Autoconf manual

[Paul Eggert]

I ran into this problem when building the Autoconf manual using Texinfo 6.3 on 
Fedora 24, which has Perl 5.22.2. With the attached file (which is a 
stripped-down version of the manual), the command 'makeinfo autoconf.texi' 
complains:

  Negative repeat count does nothing at 
/home/eggert/opt/Linux-x86_64/texinfo-6.3/share/texinfo/Texinfo/Convert/Plaintext.pm 
line 1038.
  Negative repeat count does nothing at 
/home/eggert/opt/Linux-x86_64/texinfo-6.3/share/texinfo/Texinfo/Convert/Plaintext.pm 
line 1039.

These complaints seem to be bogus. I expect this some sort of Perl compatibility 
issue.

PS. I suggest adding this as a test case for Texinfo, as it would be amusing to 
test Texinfo with Chaos....

autoconf.texi
Description: Text Data