[PATCH v3 2/4] transport.c: extract 'fill_alternate_refs_command'

[Taylor Blau <me@ttaylorr.com>]

To list alternate references, 'read_alternate_refs' creates a child
process running 'git for-each-ref' in the alternate's Git directory.

Prepare to run other commands besides 'git for-each-ref' by introducing
and moving the relevant code from 'read_alternate_refs' to
'fill_alternate_refs_command'.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 transport.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/transport.c b/transport.c
index 2e0bc414d0..2825debac5 100644
--- a/transport.c
+++ b/transport.c
@@ -1325,6 +1325,17 @@ char *transport_anonymize_url(const char *url)
 	return xstrdup(url);
 }
 
+static void fill_alternate_refs_command(struct child_process *cmd,
+					const char *repo_path)
+{
+	cmd->git_cmd = 1;
+	argv_array_pushf(&cmd->args, "--git-dir=%s", repo_path);
+	argv_array_push(&cmd->args, "for-each-ref");
+	argv_array_push(&cmd->args, "--format=%(objectname)");
+	cmd->env = local_repo_env;
+	cmd->out = -1;
+}
+
 static void read_alternate_refs(const char *path,
 				alternate_ref_fn *cb,
 				void *data)
@@ -1333,12 +1344,7 @@ static void read_alternate_refs(const char *path,
 	struct strbuf line = STRBUF_INIT;
 	FILE *fh;
 
-	cmd.git_cmd = 1;
-	argv_array_pushf(&cmd.args, "--git-dir=%s", path);
-	argv_array_push(&cmd.args, "for-each-ref");
-	argv_array_push(&cmd.args, "--format=%(objectname)");
-	cmd.env = local_repo_env;
-	cmd.out = -1;
+	fill_alternate_refs_command(&cmd, path);
 
 	if (start_command(&cmd))
 		return;
-- 
2.19.0.221.g150f307af