[PATCH 09/16] repack-midx: factor out `repack_prepare_midx_command()`

[Taylor Blau <me@ttaylorr.com>]

The `write_midx_included_packs()` function assembles and executes a
`git multi-pack-index write` command, constructing the argument list
inline.

Future commits will introduce additional callers that need to construct
similar `git multi-pack-index` commands (for both `write` and `compact`
subcommands), so extract the common portions of the command setup into a
reusable `repack_prepare_midx_command()` helper.

The extracted helper sets `git_cmd`, pushes the `multi-pack-index`
subcommand and verb, and handles `--progress`/`--no-progress` and
`--bitmap` flags. The remaining arguments that are specific to the
`write` subcommand (such as `--stdin-packs`) are left to the caller.

No functional changes are included in this patch.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 repack-midx.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/repack-midx.c b/repack-midx.c
index 0682b80c427..83151d4734a 100644
--- a/repack-midx.c
+++ b/repack-midx.c
@@ -275,6 +275,23 @@ static void remove_redundant_bitmaps(struct string_list *include,
 	strbuf_release(&path);
 }
 
+static void repack_prepare_midx_command(struct child_process *cmd,
+					struct repack_write_midx_opts *opts,
+					const char *verb)
+{
+	cmd->git_cmd = 1;
+
+	strvec_pushl(&cmd->args, "multi-pack-index", verb, NULL);
+
+	if (opts->show_progress)
+		strvec_push(&cmd->args, "--progress");
+	else
+		strvec_push(&cmd->args, "--no-progress");
+
+	if (opts->write_bitmaps)
+		strvec_push(&cmd->args, "--bitmap");
+}
+
 int write_midx_included_packs(struct repack_write_midx_opts *opts)
 {
 	struct child_process cmd = CHILD_PROCESS_INIT;
@@ -289,18 +306,9 @@ int write_midx_included_packs(struct repack_write_midx_opts *opts)
 		goto done;
 
 	cmd.in = -1;
-	cmd.git_cmd = 1;
 
-	strvec_push(&cmd.args, "multi-pack-index");
-	strvec_pushl(&cmd.args, "write", "--stdin-packs", NULL);
-
-	if (opts->show_progress)
-		strvec_push(&cmd.args, "--progress");
-	else
-		strvec_push(&cmd.args, "--no-progress");
-
-	if (opts->write_bitmaps)
-		strvec_push(&cmd.args, "--bitmap");
+	repack_prepare_midx_command(&cmd, opts, "write");
+	strvec_push(&cmd.args, "--stdin-packs");
 
 	if (preferred)
 		strvec_pushf(&cmd.args, "--preferred-pack=%s",
-- 
2.53.0.729.g817728289e1.dirty