[PATCH v3 2/9] upload-archive: use regular "struct child_process" pattern

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

This pattern added [1] in seems to have been intentional, but since
[2] and [3] we've wanted do initialization of what's now the "struct
strvec" "args" and "env_array" members. Let's not trample on that
initialization here.

1. 1bc01efed17 (upload-archive: use start_command instead of fork,
   2011-11-19)
2. c460c0ecdca (run-command: store an optional argv_array, 2014-05-15)
3. 9a583dc39e (run-command: add env_array, an optional argv_array for
   env, 2014-10-19)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 builtin/upload-archive.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/builtin/upload-archive.c b/builtin/upload-archive.c
index 24654b4c9bf..98d028dae67 100644
--- a/builtin/upload-archive.c
+++ b/builtin/upload-archive.c
@@ -77,7 +77,7 @@ static ssize_t process_input(int child_fd, int band)
 
 int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 {
-	struct child_process writer = { argv };
+	struct child_process writer = CHILD_PROCESS_INIT;
 
 	if (argc == 2 && !strcmp(argv[1], "-h"))
 		usage(upload_archive_usage);
@@ -89,9 +89,10 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 	 * multiplexed out to our fd#1.  If the child dies, we tell the other
 	 * end over channel #3.
 	 */
-	argv[0] = "upload-archive--writer";
 	writer.out = writer.err = -1;
 	writer.git_cmd = 1;
+	strvec_push(&writer.args, "upload-archive--writer");
+	strvec_pushv(&writer.args, argv + 1);
 	if (start_command(&writer)) {
 		int err = errno;
 		packet_write_fmt(1, "NACK unable to spawn subprocess\n");
-- 
2.34.1.838.g779e9098efb