0. Has the thing ever not been broken? (for first releases)

Missing or wrong install rules, tests not building or not behind CATKIN_ENABLE_TESTING, launch file problems, build order chaos, DEPENDS/CATKIN_DEPENDS confusion, various other dependency problems, especially misunderstandings around run_depend.

Not that a local prerelease can catch all that stuff, but I admit that the hassle of getting a devel job into the rosdistro meant that for me I would often release a known-broken 0.0.1 version of a package, just to get the devel job set up so that I could use the online prerelease tool to fix it up for the "real" first release.