[PATCH 2/3] hash-object doc: elaborate on -w and --literally promises

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

Clarify the hash-object docs to explicitly note that the --literally
option guarantees that a loose object will be written, but that a
normal -w ("write") invocation doesn't.

At first I thought talking about "loose object" in the docs was a
mistake in 83115ac4a8 ("git-hash-object.txt: document --literally
option", 2015-05-04), but as is clear from 5ba9a93b39 ("hash-object:
add --literally option", 2014-09-11) this was intended all along.

As seen in 4dd1fbc7b1 ("Bigfile: teach "git add" to send a large file
straight to a pack", 2011-05-08) we'll otherwise not guarantee that we
write loose objects, so let's explicitly note that, using vague enough
language to leave the door open to any arbitrary future storage
format, not just loose objects and packs.

While I'm at it remove the mention of "--stdin" from the "--literally"
documentation. This wasn't correct, the "--literally" option combines
with any other option (e.g. "--stdin-paths"), not just "--stdin".

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Documentation/git-hash-object.txt | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-hash-object.txt b/Documentation/git-hash-object.txt
index df9e2c58bd..100630d021 100644
--- a/Documentation/git-hash-object.txt
+++ b/Documentation/git-hash-object.txt
@@ -28,6 +28,12 @@ OPTIONS
 
 -w::
 	Actually write the object into the object database.
++
+No guarantees are made as to how the object is added to the database
+(e.g. whether as a loose object, or streamed to a pack), except in the
+case of the `--literally` option. How it's written may depend on
+heuristics such as the `core.bigFileThreshold` configuration variable
+(see linkgit:git-config[1]).
 
 --stdin::
 	Read the object from standard input instead of from a file.
@@ -53,10 +59,11 @@ OPTIONS
 	is always implied, unless the `--path` option is given.
 
 --literally::
-	Allow `--stdin` to hash any garbage into a loose object which might not
+	Allow for hashing arbitrary data which might not
 	otherwise pass standard object parsing or git-fsck checks. Useful for
 	stress-testing Git itself or reproducing characteristics of corrupt or
-	bogus objects encountered in the wild.
+	bogus objects encountered in the wild. When writing objects guarantees
+	that the written object will be a loose object, for ease of debugging.
 
 GIT
 ---
-- 
2.21.0.1020.gf2820cf01a