Currently when a tarball URL is not found in CPAN::Perl::Releases,
a warning WARN: [cpan_perl_releases] not found the tarball is emitted, even if it is found in MetaCPAN.
# Note that CPAN::Perl::Releases 3.56 does not have perl-5.28.0-RC1 entry
❯ perl -MCPAN::Perl::Releases\ 9999
CPAN::Perl::Releases version 9999 required--this is only version 3.56.
BEGIN failed--compilation aborted.
❯ perl -Ilib script/perl-build 5.28.0-RC1 $PWD
WARN: [cpan_perl_releases] not found the tarball for perl-5.28.0-RC1
Fetching 5.28.0-RC1 as /var/folders/9j/xylqh05507j22rcpxpfxr2mw0000gn/T/oOevBbJGNS/perl-5.28.0-RC1.tar.gz (http://www.cpan.org/authors/id/X/XS/XSAWYERX/perl-5.28.0-RC1.tar.gz)
...
I think it is enough to emit warnings only if we cannot tarball URLs in both CPAN::Perl::Releases and MetaCPAN.
Currently when a tarball URL is not found in CPAN::Perl::Releases, a warning
WARN: [cpan_perl_releases] not found the tarballis emitted, even if it is found in MetaCPAN.I think it is enough to emit warnings only if we cannot tarball URLs in both CPAN::Perl::Releases and MetaCPAN.