[BUG] spurious failure when adding tracked file in ignored directory

[Christian Sattler <sattler.christian@xxxxxxxxx>]

Adding a tracked file in an ignored directory causes a spurious warning and
exit code 1 failure (despite actually adding the file). Example on 2.47.0:

git init
mkdir dir
touch dir/file
git add dir/file
echo dir >.gitignore
git add dir/file

The last command fails with exit code 1 and prints:

> The following paths are ignored by one of your .gitignore files:
> dir
> hint: Use -f if you really want to add them.
> hint: Disable this message with "git config advice.addIgnoredFile false"

Suppose we change dir/file before the last command.  Then after the last
command, the change is in the index, despite what the warning indicates.

- Christian