Missing "Section:" of source package causes upload failure

[Balint Reczey]

When building a package in a PPA if "Section:" field is missing from the "Source:" group in debian/control the upload is rejected:

DEBUG Considering changefile 86522/ubuntu/bglibs_1.106-3_arm64.changes
DEBUG Finding fresh policy
INFO Processing upload bglibs_1.106-3_arm64.changes
INFO Upload was rejected:
INFO bglibs_1.106-3_arm64.buildinfo: Unknown section '-'
INFO Further error processing not possible because of a critical previous error.
INFO Committing the transaction and any mails associated with this upload.

https://launchpadlibrarian.net/322145336/buildlog_ubuntu-artful-arm64.bglibs_1.106-3_BUILDING.txt.gz

test:~/bglibs-1.106$ cat debian/control
Source: bglibs
Priority: optional
Maintainer: Debian QA Group <email address hidden>
Build-Depends: libtool, libtool-bin
Standards-Version: 3.9.8

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