[PATCH 1/1] add --edit: truncate the patch file

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

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

If there is already a .git/ADD_EDIT.patch file, we fail to truncate it
properly, which could result in very funny errors.

Of course, this file should not be left lying around. But at least in
one case, there was a stale copy, larger than the current diff. So the
result was a corrupt diff.

Let's just truncate the file when we write it and not worry about it too
much.

Reported by J Wyman.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/add.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/builtin/add.c b/builtin/add.c
index f65c172299..53c18ea429 100644
--- a/builtin/add.c
+++ b/builtin/add.c
@@ -239,7 +239,7 @@ static int edit_patch(int argc, const char **argv, const char *prefix)
 	rev.diffopt.output_format = DIFF_FORMAT_PATCH;
 	rev.diffopt.use_color = 0;
 	rev.diffopt.flags.ignore_dirty_submodules = 1;
-	out = open(file, O_CREAT | O_WRONLY, 0666);
+	out = open(file, O_CREAT | O_WRONLY | O_TRUNC, 0666);
 	if (out < 0)
 		die(_("Could not open '%s' for writing."), file);
 	rev.diffopt.file = xfdopen(out, "w");
-- 
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