[PATCH 1/2] built-in add -i: do not try to `patch`/`diff` an empty list of files

["Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>]

From: Johannes Schindelin <johannes.schindelin@gmx.de>

When the user does not select any files to `patch` or `diff`, there is
no need to call `run_add_p()` on them.

Even worse: we _have_ to avoid calling `parse_pathspec()` with an empty
list because that would trigger this error:

	BUG: pathspec.c:557: PATHSPEC_PREFER_CWD requires arguments

So let's avoid doing any work on a list of files that is empty anyway.

This fixes https://github.com/git-for-windows/git/issues/2466.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 add-interactive.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/add-interactive.c b/add-interactive.c
index f395d54c08..14d4688c26 100644
--- a/add-interactive.c
+++ b/add-interactive.c
@@ -915,7 +915,7 @@ static int run_patch(struct add_i_state *s, const struct pathspec *ps,
 
 	opts->prompt = N_("Patch update");
 	count = list_and_choose(s, files, opts);
-	if (count >= 0) {
+	if (count > 0) {
 		struct argv_array args = ARGV_ARRAY_INIT;
 
 		argv_array_pushl(&args, "git", "add--interactive", "--patch",
@@ -953,7 +953,7 @@ static int run_diff(struct add_i_state *s, const struct pathspec *ps,
 	opts->flags = IMMEDIATE;
 	count = list_and_choose(s, files, opts);
 	opts->flags = 0;
-	if (count >= 0) {
+	if (count > 0) {
 		struct argv_array args = ARGV_ARRAY_INIT;
 
 		argv_array_pushl(&args, "git", "diff", "-p", "--cached",
-- 
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