hairloss, due to agvtool

The undocumented option -increment-minor-version is what I needed, such as in

agvtool bump -increment-minor-version

to bump the version from 0.0.1 to 0.0.2, instead of just 1 to 2 for instance.

I find it particularly inconvenient, that this tool updates the DYLIB_CURRENT_VERSION and well as the CURRENT_PROJECT_VERSION, when you could just set the DYLIB_CURRENT_VERSION like

DYLIB_CURRENT_VERSION=$(CURRENT_PROJECT_VERSION)

in the project file