Replace parse_blob() with an explanatory comment

parse_blob() has never actually been used; it has served simply to
avoid having a confusing gap in the API. Instead of leaving it, put in
a comment that explains what "parsing a blob" entails (making sure the
object is actually readable), and why code might care whether a blob
has been parsed or not.

Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

blob.c

@@ -23,24 +23,3 @@ int parse_blob_buffer(struct blob *item, void *buffer, unsigned long size)
 	item->object.parsed = 1;
 	return 0;
 }
-
-int parse_blob(struct blob *item)
-{
-        enum object_type type;
-        void *buffer;
-        unsigned long size;
-	int ret;
-
-        if (item->object.parsed)
-                return 0;
-        buffer = read_sha1_file(item->object.sha1, &type, &size);
-        if (!buffer)
-                return error("Could not read %s",
-                             sha1_to_hex(item->object.sha1));
-        if (type != OBJ_BLOB)
-                return error("Object %s not a blob",
-                             sha1_to_hex(item->object.sha1));
-	ret = parse_blob_buffer(item, buffer, size);
-	free(buffer);
-	return ret;
-}

blob.h

@@ -13,6 +13,13 @@ struct blob *lookup_blob(const unsigned char *sha1);
 
 int parse_blob_buffer(struct blob *item, void *buffer, unsigned long size);
 
-int parse_blob(struct blob *item);
+/**
+ * Blobs do not contain references to other objects and do not have
+ * structured data that needs parsing. However, code may use the
+ * "parsed" bit in the struct object for a blob to determine whether
+ * its content has been found to actually be available, so
+ * parse_blob_buffer() is used (by object.c) to flag that the object
+ * has been read successfully from the database.
+ **/
 
 #endif /* BLOB_H */