Simple test: does `rpmbuild` require single-digit days in `%changelog`?

_el6_session.log

[build_user@6d76bec03a81 ~]$ rpmlint -i foo.spec 
foo.spec: W: no-buildroot-tag
The BuildRoot tag isn't used in your spec. It must be used in order to allow
building the package as non root on some systems. For some rpm versions (e.g.
rpm.org >= 4.6) the BuildRoot tag is not necessary in specfiles and is ignored
by rpmbuild; if your package is only going to be built with such rpm versions
you can ignore this warning.

0 packages and 1 specfiles checked; 0 errors, 1 warnings.
[build_user@6d76bec03a81 ~]$ rpm --version
RPM version 4.8.0
[build_user@6d76bec03a81 ~]$ rpmbuild -ba foo.spec  &> /dev/null && echo worked || echo failed
worked
[build_user@6d76bec03a81 ~]$ rpm -qp /home/build_user/rpmbuild/RPMS/x86_64/foo-1.0.0-1.el6.x86_64.rpm --changelog
* Thu Mar 01 2018 Foo F. McFoobody <foo@foofoo.foo>
- foo

_el7_session.log

[build_user@cdde26d09721 ~]$ rpmlint foo.spec 
0 packages and 1 specfiles checked; 0 errors, 0 warnings.
[build_user@cdde26d09721 ~]$ rpmbuild -ba foo.spec  &> /dev/null && echo worked || echo failed
worked
[build_user@cdde26d09721 ~]$ rpm -qp /home/build_user/rpmbuild/RPMS/x86_64/foo-1.0.0-1.el7.centos.x86_64.rpm --changelog
* Thu Mar 01 2018 Foo F. McFoobody <foo@foofoo.foo>
- foo

foo.spec

Name:           foo
Version:        1.0.0
Release:        1%{?dist}
Summary:        foo
License:        foo

%description
foo

%build

%prep

%install
rm -rf %{buildroot}
mkdir -p %{buildroot}
echo foo > %{buildroot}/foo

%clean
rm -rf %{buildroot}/foo

%files
%attr(-, root, root) /foo

%changelog
* Thu Mar 1 2018 Foo F. McFoobody <foo@foofoo.foo>
- foo