displayed, indented N places. If a commit is on the I-th
branch, the I-th indentation character shows a '+' sign;
otherwise it shows a space. Each commit shows a short name that
-can be used as an exended SHA1 to name that commit.
+can be used as an extended SHA1 to name that commit.
The following example shows three branches, "master", "fixes"
and "mhf":