The changeset (or "diff") of each commit between the fork-point and <head>
is compared against each commit between the fork-point and <upstream>.
-Every commit with a changeset that doesn't exist in the other branch
-has its id (sha1) reported, prefixed by a symbol. Those existing only
+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.