When a kernel subsystem maintainer has a set of commits to send up the
chain toward the mainline, the git request-pull
command is usually
the right tool for the job. But various maintainers have noticed over the
years that this command can sometimes generate confusing results when
confronted with anything but the simplest of histories. A brief
conversation on the linux-kernel mailing list delved into why this
situation comes about and what maintainers can do in response.

Source: LWN.net – [$] “git request-pull” and confusing diffstats