Merge branch 'jk/add-i-read-error'

"git add -i" did not notice when the interactive command input
stream went away and kept asking.

* jk/add-i-read-error:
  add--interactive: leave main loop on read error

git-add--interactive.perl

@@ -1356,6 +1356,7 @@ sub patch_update_file {
 		  $patch_mode_flavour{TARGET},
 		  " [y,n,q,a,d,/$other,?]? ";
 		my $line = prompt_single_character;
+		last unless defined $line;
 		if ($line) {
 			if ($line =~ /^y/i) {
 				$hunk[$ix]{USE} = 1;