Default section in d/control is unknown

[bafu]

reprepro will report warning when including model package:

$ reprepro includedeb stretch ~/tinyyolo_20170816_all.deb 
Warning: strange section 'unknown'!
Exporting indices...

Generated d/control example:

$ cat control 
Source: tinyyolo
Section: unknown
Priority: optional
Maintainer: Bofu Chen (bafu) <[email protected]>
Build-Depends: debhelper (>=9)
Standards-Version: 3.9.6
Homepage: <insert the upstream URL, if relevant>
#Vcs-Git: git://anonscm.debian.org/collab-maint/tinyyolo.git
#Vcs-Browser: https://anonscm.debian.org/cgit/collab-maint/tinyyolo.git

Package: tinyyolo
Architecture: all
Depends: ${misc:Depends}
Description: <insert up to 60 chars description>
 <insert long description, indented with spaces>