Add post-merge hook, related documentation, and tests.

diff --git a/cache-tree.c b/cache-tree.c
index 350a79b768e7c032e1b4815f7201c9ce5f88bc8d..077f03436941e9c0bf31d3bb2002c1e36b8817b9 100644 (file)
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -478,7 +478,7 @@ static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
        if (0 <= it->entry_count) {
                if (size < 20)
                        goto free_return;
-               hashcpy(it->sha1, (unsigned char*)buf);
+               hashcpy(it->sha1, (const unsigned char*)buf);
                buf += 20;
                size -= 20;
        }