Hiding HEAD~10 is not the same as log -10

Passing -10 to git-log makes it limit the amount of commits it will
handle (output). Hiding HEAD~10 stops processing at the 10th
grandparent of the current commit through the first-parent line, which
is what ^HEAD~10 does.

The only time these two options will produce the same output is when
there are no merges between HEAD and HEAD~10. In any other case, they
will produce output which can be vastly different.

---

For example, in libgit2:

````
% git log --oneline HEAD ^HEAD~10 | wc -l
30
% git log --oneline -10 HEAD | wc -l     
10
````