[PATCH v2 1/4] pack-write: make index-pack output comment hash agnostic

[Justin Tobler <jltobler@gmail.com>]

The code comment in `index_pack_lockfile()` explains the expected format
of output from git-index-pack(1). As written it explicitly mentions
SHA1, but both the git-index-pack(1) output and the parsing are not
specific to SHA1 and also support SHA256.

Update the comment explanation to be hash agnostic accordingly.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
---
 pack-write.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/pack-write.c b/pack-write.c
index 85674e4b72..b1311c9923 100644
--- a/pack-write.c
+++ b/pack-write.c
@@ -476,11 +476,15 @@ char *index_pack_lockfile(struct odb_source *source, int ip_out,
 	const int len = source->odb->repo->hash_algo->hexsz + 6;
 
 	/*
-	 * The first thing we expect from index-pack's output
-	 * is "pack\t%40s\n" or "keep\t%40s\n" (46 bytes) where
-	 * %40s is the newly created pack SHA1 name.  In the "keep"
-	 * case, we need it to remove the corresponding .keep file
-	 * later on.  If we don't get that then tough luck with it.
+	 * The first thing we expect from index-pack's output is
+	 * "pack\t<name>\n" or "keep\t<name>\n", where <name> is the hexadecimal
+	 * name of the packfile it has just written. The line is therefore five
+	 * bytes of prefix, `hexsz` bytes of name, and a trailing newline. A
+	 * "keep" prefix tells us that index-pack has also created the
+	 * corresponding ".keep" file.
+	 *
+	 * In the "keep" case, we need it to remove the corresponding ".keep"
+	 * file later on. If we don't get that then tough luck with it.
 	 */
 	if (read_in_full(ip_out, packname, len) == len && packname[len-1] == '\n') {
 		const char *name;
-- 
2.56.0.173.gf57c9a7388