Merge branch 'jc/checkout-out-of-unborn' into maint

* jc/checkout-out-of-unborn:
  git checkout -b: allow switching out of an unborn branch

diff --cc builtin/checkout.c
index f1984d9933c526bcd2af66fd745dc64a607ac19b,b76e2c0451cbeb73e1fd227c343413b1c8a33cc7..a76aa2a6fd6ad076f4d10e4f5227d24b31c063ca
--- 1/builtin/checkout.c
--- 2/builtin/checkout.c
+++ b/builtin/checkout.c
@@@ -1093,5 -1100,13 +1104,13 @@@ int cmd_checkout(int argc, const char *
        if (opts.writeout_stage)
                die(_("--ours/--theirs is incompatible with switching branches."));
  
 -              resolve_ref("HEAD", rev, 0, &flag);
 -              if ((flag & REF_ISSYMREF) && is_null_sha1(rev))
+       if (!new.commit) {
+               unsigned char rev[20];
+               int flag;
+ 
++              if (!read_ref_full("HEAD", rev, 0, &flag) &&
++                  (flag & REF_ISSYMREF) && is_null_sha1(rev))
+                       return switch_unborn_to_new_branch(&opts);
+       }
        return switch_branches(&opts, &new);
  }