Every commit that doesn't exist in the <upstream> branch has its id (sha1) reported, prefixed by a symbol. The ones that have equivalent change already in the <upstream> branch are prefixed with a minus (-) sign, and those that only exist in the <head> branch are prefixed with a plus (+) symbol:
__*__*__*__*__> <upstream>
/
fork-point
\__+__+__-__+__+__-__+__> <head>
If a <limit> has been given then the commits along the
<head> branch up to and including <limit> are not
reported:
__*__*__*__*__> <upstream>
/
fork-point
\__*__*__<limit>__-__+__> <head>
Because git-cherry compares the changeset rather than the commit id
(sha1), you can use git-cherry to find out if a commit you made
locally has been applied <upstream> under a different commit
id. For example, this will happen if you're feeding patches
<upstream> via email rather than pushing or pulling commits
directly.