Re: [PATCH v3 1/3] builtin/config: introduce `--default`

Taylor Blau [off-list ref] writes:

For some use cases, callers of the `git-config(1)` builtin would like to
fallback to default values when the slot asked for does not exist. In
addition, users would like to use existing type specifiers to ensure
that values are parsed correctly when they do exist in the
configuration.
...
+--default value::
+  When using `--get`, and the requested slot is not found, behave as if value
+  were the value assigned to the that slot.

For "diff.<slot>.color", the above is OK, but in general,
configuration variables are not called "slot".  s/slot/variable/.