fpm 1.12.0 adds an unintended runtime dependency on git, which should be
fixed in a future release. Pin fpm for now since installing git has its
own side effects, such as installing less and changing the default pager
on systems where less isn't available by default.
/usr/bin/pager is specific to Debian/Ubuntu. For other OSs, use the default
pager detected by the configure script, which will either be less or more.
See https://github.com/rstudio/r-builds/issues/3
