[PATCH v3 05/13] send-email: copy "config_regxp" into git-send-email.perl

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

The config_regexp() function was added in dd84e528a3 (git-send-email:
die if sendmail.* config is set, 2020-07-23) for use in
git-send-email, and it's the only in-tree user of it.

However, the consensus is that Git.pm is a public interface, so even
though it's a recently added function we can't change it. So let's
copy over a minimal version of it to git-send-email.perl itself. In a
subsequent commit it'll be changed further for our own use.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 git-send-email.perl | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/git-send-email.perl b/git-send-email.perl
index 3d8362b5f0..95a69d4c51 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -380,6 +380,24 @@ sub read_config {
 	}
 }
 
+sub config_regexp {
+	my ($regex) = @_;
+	my @ret;
+	eval {
+		@ret = Git::command(
+			'config',
+			'--name-only',
+			'--get-regexp',
+			$regex,
+		);
+		1;
+	} or do {
+		# If we have no keys we're OK, otherwise re-throw
+		die $@ if $@->value != 1;
+	};
+	return @ret;
+}
+
 # sendemail.identity yields to --identity. We must parse this
 # special-case first before the rest of the config is read.
 $identity = Git::config(@repo, "sendemail.identity");
@@ -478,7 +496,7 @@ sub read_config {
     usage();
 }
 
-if ($forbid_sendmail_variables && (scalar Git::config_regexp("^sendmail[.]")) != 0) {
+if ($forbid_sendmail_variables && (scalar config_regexp("^sendmail[.]")) != 0) {
 	die __("fatal: found configuration options for 'sendmail'\n" .
 		"git-send-email is configured with the sendemail.* options - note the 'e'.\n" .
 		"Set sendemail.forbidSendmailVariables to false to disable this check.\n");
-- 
2.32.0.rc0.406.g05cb3eebfc