patchgit-send-email: Respect core.hooksPath setting

> get-send-email currently makes the assumption that the
> 'sendemail-validate' hook exists inside of the repository.
>
> Since the introduction of `core.hooksPath` configuration option in
> v2.9, this is no longer true.
>
> Instead of assuming a hardcoded repo relative path, query
> git for the actual path of the hooks directory.
>
> Signed-off-by: Robert Foss <robert.foss@linaro.org>
> ---
>
>
> This patch does not include a test for this bug fix.
> This is entirely due to me not being able to think up a way
> to test this. So I'm very much open to suggestions.

>  git-send-email.perl | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/git-send-email.perl b/git-send-email.perl
> index 1f425c0809..3934dceb70 100755
> --- a/git-send-email.perl
> +++ b/git-send-email.perl
> @@ -1942,8 +1942,9 @@ sub validate_patch {
>  	my ($fn, $xfer_encoding) = @_;
>  
>  	if ($repo) {
> -		my $validate_hook = catfile(catdir($repo->repo_path(), 'hooks'),
> -					    'sendemail-validate');
> +		my $hook_path = $repo->command('rev-parse', '--git-path', 'hooks');
> +		chomp($hook_path);
> +		my $validate_hook = catfile($hook_path, 'sendemail-validate');

>
>
> On Mon, Mar 22 2021, Robert Foss wrote:
>
> > get-send-email currently makes the assumption that the
> > 'sendemail-validate' hook exists inside of the repository.
> >
> > Since the introduction of `core.hooksPath` configuration option in
> > v2.9, this is no longer true.
> >
> > Instead of assuming a hardcoded repo relative path, query
> > git for the actual path of the hooks directory.
> >
> > Signed-off-by: Robert Foss <robert.foss@linaro.org>
> > ---
> >
> >
> > This patch does not include a test for this bug fix.
> > This is entirely due to me not being able to think up a way
> > to test this. So I'm very much open to suggestions.
>
> There's an "invoke hook" test in t9001-send-email.sh which should be
> easy to tweak (or mostly copy/pasted to another test) to run the same
> way once the hook is moved from .git/hooks to somedir/ and -c
> core.hooksPath=somedir is set.

>
> >  git-send-email.perl | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/git-send-email.perl b/git-send-email.perl
> > index 1f425c0809..3934dceb70 100755
> > --- a/git-send-email.perl
> > +++ b/git-send-email.perl
> > @@ -1942,8 +1942,9 @@ sub validate_patch {
> >       my ($fn, $xfer_encoding) = @_;
> >
> >       if ($repo) {
> > -             my $validate_hook = catfile(catdir($repo->repo_path(), 'hooks'),
> > -                                         'sendemail-validate');
> > +             my $hook_path = $repo->command('rev-parse', '--git-path', 'hooks');
> > +             chomp($hook_path);
> > +             my $validate_hook = catfile($hook_path, 'sendemail-validate');
>
> This looks like it work, small nits:
>
> 1. This would be better in perl/Git.pm, it already has various accessors
>    etc. for these rev-parse'd values. You could just pass a a new
>    GetHooksPath => 1 to Git->repository() and if so populate this, then
>    call that as $repo->git_path_hooks.

>
> 2. FWIW it's more idiomatic in perl to just do : chomp(my $x = y()); not
>    my $x = y(); chomp $x. The chomp operator works in-place, but once
>    you'd use the helpers in Git.pm for this they'd do all that for you.
>
> >               my $hook_error;
> >               if (-x $validate_hook) {
> >                       my $target = abs_path($fn);
>