Merge branch 'sr/add--interactive-term-readkey'

* sr/add--interactive-term-readkey:
  git-add--interactive: warn if module for interactive.singlekey is missing
  git-config: document interactive.singlekey requires Term::ReadKey

Documentation/config.txt

@@ -1643,7 +1643,7 @@ interactive.singlekey::
 	linkgit:git-add[1], linkgit:git-checkout[1], linkgit:git-commit[1],
 	linkgit:git-reset[1], and linkgit:git-stash[1]. Note that this
 	setting is silently ignored if portable keystroke input
-	is not available.
+	is not available; requires the Perl module Term::ReadKey.
 
 log.abbrevCommit::
 	If true, makes linkgit:git-log[1], linkgit:git-show[1], and

git-add--interactive.perl

@@ -58,6 +58,9 @@
 		Term::ReadKey->import;
 		$use_readkey = 1;
 	};
+	if (!$use_readkey) {
+		print STDERR "missing Term::ReadKey, disabling interactive.singlekey\n";
+	}
 	eval {
 		require Term::Cap;
 		my $termcap = Term::Cap->Tgetent;