Merge branch 'mw/alternates' into next

* mw/alternates:
clone: don't clone the info/alternates file
test case for transitive info/alternates
Transitively read alternatives
repack: honor -d even when no new pack was created
clone: keep --reference even with -l -s
repo-config: document what value_regexp does a bit more clearly.
Release config lock if the regex is invalid
core-tutorial.txt: escape asterisk
Sparse fix for builtin-diff
Fix users of prefix_path() to free() only when necessary

diff --combined builtin-diff.c
index 20873162f98478b60b069e97305ab34425c5dde4,d3ac581f291dae630478248133344e2dd6a80b06..71742aa10b3b8e2621eecd4be929946b0a308deb
--- 1/builtin-diff.c
--- 2/builtin-diff.c
+++ b/builtin-diff.c
@@@ -84,8 -84,7 +84,7 @@@ static void stuff_change(struct diff_op
  
        if (opt->reverse_diff) {
                unsigned tmp;
-               const
-                       const unsigned char *tmp_u;
+               const unsigned char *tmp_u;
                const char *tmp_c;
                tmp = old_mode; old_mode = new_mode; new_mode = tmp;
                tmp_u = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_u;
@@@ -232,7 -231,7 +231,7 @@@ static int builtin_diff_combined(struc
        return 0;
  }
  
 -static void add_head(struct rev_info *revs)
 +void add_head(struct rev_info *revs)
  {
        unsigned char sha1[20];
        struct object *obj;