Re: [PATCH 02/10] t9801: use `--` in preparation for default branch rename

"Johannes Schindelin via GitGitGadget" [off-list ref]
writes:

From: Johannes Schindelin <redacted>

Seeing as we want to use `main` as the new default branch name used by
`git init`, and that `main` is used as directory name in t9801, let's
tighten the rev-list arguments to make it explicit when we are referring
to a ref instead of a directory.

Interesting.  s/master/main/g would introduce "that name is both a
revision and a path" ambiguity?  An obvious alternative would be to
use a word that is not 'main' or 'master' for the path and that way
we will keep the current property that tests do not have to worry
about the rev/path ambiguity.  But given that even "git p4" should
be safe against rev/path ambiguity, I think this is good in the long
run---if "git p4" is not prepared to handle the ambiguity correctly,
then this approach may reveal such an existing breakage when the
branch name 'master' is replaced with 'main', and at that point, we
have to scramble and fix it (or rename the path from 'main' to
something else as a workaround).

Looking good.