[SRU] Missing static libs in the -dev package metadata

[Jose Luis Rivero]

[Impact]

 * The libgazebo9-dev does not include the static libs generated
   during the gazebo build.
   Users of gazebo binaries can not access to them through the
   normal package.

 * At this moment there is only one .a library being generated
   (libgazebo_test_fixture.a). This can be checked in the build log:

https://launchpadlibrarian.net/358995329/buildlog_ubuntu-bionic-amd64.gazebo_9.0.0+dfsg5-3ubuntu1_BUILDING.txt.gz (search for Linking CXX static library)

 * The change in the packaging metadata should make the new -dev package
   to ship the static libraries.

[Test Case]

 * To trigger the bug:
   apt-get install libgazebo9-dev && find /usr/lib -name libgazebo_*.a && echo "static lib found" || echo "no static lib found"

[Regression Potential]

 * The change does not modify in any way any of the current files being
   packed but add more regexp to the install fix.

 * Upstream debian custom packages made this change long ago and there
   was no problem reported:

https://bitbucket.org/osrf/gazebo9-release/src/7b7893d6674b0059b2378b7b912f48cc001aeaa4/ubuntu/debian/libgazebo-dev.install#lines-2

[Other Info]

 * I'm part of Gazebo upstream and the debian maintainer.

[Simon Quigley (tsimonq2)]

I'm subscribing the SRU team to get their opinion prior to sponsoring it.

[Jose Luis Rivero (j-rivero)]

Friendly ping. The bug is affecting most of the Bionic CI mechanisms that uses the gazebo simulator. i.e. https://github.com/ros-simulation/gazebo_ros_pkgs/pull/796#issuecomment-411387717

[Jeremy Bícha (jbicha)]

Jose, Ubuntu Stable Release Update policy requires that bugs be fixed in the current development release (currently Ubuntu 18.10 "cosmic") before being fixed in stable release updates.

See #1 of https://wiki.ubuntu.com/StableReleaseUpdates#Procedure

Since gazebo is mostly maintained by Debian, I strongly encourage you to file this bug in Debian first. If you've never reported a bug in Debian before, this page may help:
https://wiki.ubuntu.com/Debian/Bugs

[Robie Basak (racb)]

Please could you also add an "explanation of the bug on users and justification for backporting the fix to the stable release"? I don't feel that your current Impact section explains this. After reading it I still have the question "how does this impact users?".

[Jose Luis Rivero (j-rivero)]

Jeremy: thanks for the pointer. You were right Gazebo was not updated at that moment. I've update it during the last months and Debian and disco-proposed both have 9.6.0 which include the fix to this problem.

Robie: sorry for not being clear about the effects of the bug. The lack of the library libgazebo_test_fixture.a in the Ubuntu packages is making some users not to be able to use the test feature since their code can not link against it. Example: https://bitbucket.org/osrf/gazebo/issues/2299/how-to-run-gazebo-integrated-unit-test#comment-38049019