add -p: only bind search key if there's more than one hunk

If there is only a single hunk then disable searching as there is
nothing to search for. Also print a specific error message if the user
tries to search with '/' when there's only a single hunk rather than
just listing the key bindings.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-add--interactive.perl

@@ -1185,7 +1185,7 @@ d - do not apply this hunk or any of the later hunks in the file"),
 sub help_patch_cmd {
 	local $_;
-	my $other = $_[0] . ",/,?";
+	my $other = $_[0] . ",?";
 	print colored $help_color, __($help_patch_modes{$patch_mode}), "\n",
 		map { "$_\n" } grep {
 			my $c = quotemeta(substr($_, 0, 1));
@@ -1308,39 +1308,39 @@ sub display_hunks {
 my %patch_update_prompt_modes = (
 	stage => {
-		mode => N__("Stage mode change [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Stage deletion [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Stage this hunk [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Stage mode change [y,n,q,a,d%s,?]? "),
+		deletion => N__("Stage deletion [y,n,q,a,d%s,?]? "),
+		hunk => N__("Stage this hunk [y,n,q,a,d%s,?]? "),
 	},
 	stash => {
-		mode => N__("Stash mode change [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Stash deletion [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Stash this hunk [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Stash mode change [y,n,q,a,d%s,?]? "),
+		deletion => N__("Stash deletion [y,n,q,a,d%s,?]? "),
+		hunk => N__("Stash this hunk [y,n,q,a,d%s,?]? "),
 	},
 	reset_head => {
-		mode => N__("Unstage mode change [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Unstage deletion [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Unstage this hunk [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Unstage mode change [y,n,q,a,d%s,?]? "),
+		deletion => N__("Unstage deletion [y,n,q,a,d%s,?]? "),
+		hunk => N__("Unstage this hunk [y,n,q,a,d%s,?]? "),
 	},
 	reset_nothead => {
-		mode => N__("Apply mode change to index [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Apply deletion to index [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Apply this hunk to index [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Apply mode change to index [y,n,q,a,d%s,?]? "),
+		deletion => N__("Apply deletion to index [y,n,q,a,d%s,?]? "),
+		hunk => N__("Apply this hunk to index [y,n,q,a,d%s,?]? "),
 	},
 	checkout_index => {
-		mode => N__("Discard mode change from worktree [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Discard deletion from worktree [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Discard this hunk from worktree [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Discard mode change from worktree [y,n,q,a,d%s,?]? "),
+		deletion => N__("Discard deletion from worktree [y,n,q,a,d%s,?]? "),
+		hunk => N__("Discard this hunk from worktree [y,n,q,a,d%s,?]? "),
 	},
 	checkout_head => {
-		mode => N__("Discard mode change from index and worktree [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Discard deletion from index and worktree [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Discard this hunk from index and worktree [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Discard mode change from index and worktree [y,n,q,a,d%s,?]? "),
+		deletion => N__("Discard deletion from index and worktree [y,n,q,a,d%s,?]? "),
+		hunk => N__("Discard this hunk from index and worktree [y,n,q,a,d%s,?]? "),
 	},
 	checkout_nothead => {
-		mode => N__("Apply mode change to index and worktree [y,n,q,a,d,/%s,?]? "),
-		deletion => N__("Apply deletion to index and worktree [y,n,q,a,d,/%s,?]? "),
-		hunk => N__("Apply this hunk to index and worktree [y,n,q,a,d,/%s,?]? "),
+		mode => N__("Apply mode change to index and worktree [y,n,q,a,d%s,?]? "),
+		deletion => N__("Apply deletion to index and worktree [y,n,q,a,d%s,?]? "),
+		hunk => N__("Apply this hunk to index and worktree [y,n,q,a,d%s,?]? "),
 	},
 );
@@ -1396,7 +1396,7 @@ sub patch_update_file {
 			$other .= ',J';
 		}
 		if ($num > 1) {
-			$other .= ',g';
+			$other .= ',g,/';
 		}
 		for ($i = 0; $i < $num; $i++) {
 			if (!defined $hunk[$i]{USE}) {
@@ -1484,6 +1484,10 @@ sub patch_update_file {
 			}
 			elsif ($line =~ m|^/(.*)|) {
 				my $regex = $1;
+				unless ($other =~ m|/|) {
+					error_msg __("No other hunks to search\n");
+					next;
+				}
 				if ($1 eq "") {
 					print colored $prompt_color, __("search for regex? ");
 					$regex = <STDIN>;