Merge branch 'ft/transport-report-segv' into maint

A failure to push due to non-ff while on an unborn branch
dereferenced a NULL pointer when showing an error message.

* ft/transport-report-segv:
push: fix segfault when HEAD points nowhere

diff --combined transport.c
index 9932f402dfee2605dbb498b120813aebaa3961f8,af442af329275a693fa713aa5ae9af759f4d4a2a..b9306ef64543d4eb705354ac170d9acc7b735ec5
--- 1/transport.c
--- 2/transport.c
+++ b/transport.c
@@@ -11,7 -11,6 +11,7 @@@
  #include "branch.h"
  #include "url.h"
  #include "submodule.h"
 +#include "string-list.h"
  
  /* rsync support */
  
@@@ -518,7 -517,8 +518,7 @@@ static int fetch_refs_via_pack(struct t
                               int nr_heads, struct ref **to_fetch)
  {
        struct git_transport_data *data = transport->data;
 -      char **heads = xmalloc(nr_heads * sizeof(*heads));
 -      char **origh = xmalloc(nr_heads * sizeof(*origh));
 +      struct string_list sought = STRING_LIST_INIT_DUP;
        const struct ref *refs;
        char *dest = xstrdup(transport->url);
        struct fetch_pack_args args;
@@@ -537,7 -537,7 +537,7 @@@
        args.depth = data->options.depth;
  
        for (i = 0; i < nr_heads; i++)
 -              origh[i] = heads[i] = xstrdup(to_fetch[i]->name);
 +              string_list_append(&sought, to_fetch[i]->name);
  
        if (!data->got_remote_heads) {
                connect_setup(transport, 0, 0);
@@@ -547,7 -547,7 +547,7 @@@
  
        refs = fetch_pack(&args, data->fd, data->conn,
                          refs_tmp ? refs_tmp : transport->remote_refs,
 -                        dest, nr_heads, heads, &transport->pack_lockfile);
 +                        dest, &sought, &transport->pack_lockfile);
        close(data->fd[0]);
        close(data->fd[1]);
        if (finish_connect(data->conn))
@@@ -557,7 -557,10 +557,7 @@@
  
        free_refs(refs_tmp);
  
 -      for (i = 0; i < nr_heads; i++)
 -              free(origh[i]);
 -      free(origh);
 -      free(heads);
 +      string_list_clear(&sought, 0);
        free(dest);
        return (refs ? 0 : -1);
  }
@@@ -741,7 -744,7 +741,7 @@@ void transport_print_push_status(const 
                        n += print_one_push_status(ref, dest, n, porcelain);
                if (ref->status == REF_STATUS_REJECT_NONFASTFORWARD &&
                    *nonfastforward != NON_FF_HEAD) {
-                       if (!strcmp(head, ref->name))
+                       if (head != NULL && !strcmp(head, ref->name))
                                *nonfastforward = NON_FF_HEAD;
                        else
                                *nonfastforward = NON_FF_OTHER;
@@@ -1010,25 -1013,6 +1010,25 @@@ void transport_set_verbosity(struct tra
                transport->progress = verbosity >= 0 && isatty(2);
  }
  
 +static void die_with_unpushed_submodules(struct string_list *needs_pushing)
 +{
 +      int i;
 +
 +      fprintf(stderr, "The following submodule paths contain changes that can\n"
 +                      "not be found on any remote:\n");
 +      for (i = 0; i < needs_pushing->nr; i++)
 +              printf("  %s\n", needs_pushing->items[i].string);
 +      fprintf(stderr, "\nPlease try\n\n"
 +                      "       git push --recurse-submodules=on-demand\n\n"
 +                      "or cd to the path and use\n\n"
 +                      "       git push\n\n"
 +                      "to push them to a remote.\n\n");
 +
 +      string_list_clear(needs_pushing, 0);
 +
 +      die("Aborting.");
 +}
 +
  int transport_push(struct transport *transport,
                   int refspec_nr, const char **refspec, int flags,
                   int *nonfastforward)
@@@ -1069,27 -1053,12 +1069,27 @@@
                        flags & TRANSPORT_PUSH_MIRROR,
                        flags & TRANSPORT_PUSH_FORCE);
  
 -              if ((flags & TRANSPORT_RECURSE_SUBMODULES_CHECK) && !is_bare_repository()) {
 +              if ((flags & TRANSPORT_RECURSE_SUBMODULES_ON_DEMAND) && !is_bare_repository()) {
                        struct ref *ref = remote_refs;
                        for (; ref; ref = ref->next)
                                if (!is_null_sha1(ref->new_sha1) &&
 -                                  check_submodule_needs_pushing(ref->new_sha1,transport->remote->name))
 -                                      die("There are unpushed submodules, aborting.");
 +                                  !push_unpushed_submodules(ref->new_sha1,
 +                                          transport->remote->name))
 +                                  die ("Failed to push all needed submodules!");
 +              }
 +
 +              if ((flags & (TRANSPORT_RECURSE_SUBMODULES_ON_DEMAND |
 +                            TRANSPORT_RECURSE_SUBMODULES_CHECK)) && !is_bare_repository()) {
 +                      struct ref *ref = remote_refs;
 +                      struct string_list needs_pushing;
 +
 +                      memset(&needs_pushing, 0, sizeof(struct string_list));
 +                      needs_pushing.strdup_strings = 1;
 +                      for (; ref; ref = ref->next)
 +                              if (!is_null_sha1(ref->new_sha1) &&
 +                                  find_unpushed_submodules(ref->new_sha1,
 +                                          transport->remote->name, &needs_pushing))
 +                                      die_with_unpushed_submodules(&needs_pushing);
                }
  
                push_ret = transport->push_refs(transport, remote_refs, flags);
@@@ -1194,7 -1163,7 +1194,7 @@@ int transport_disconnect(struct transpo
  }
  
  /*
 - * Strip username (and password) from an url and return
 + * Strip username (and password) from a URL and return
   * it in a newly allocated string.
   */
  char *transport_anonymize_url(const char *url)