push: factor out the detached HEAD error message

With push.default set to upstream or simple, and a detached HEAD, git
push prints the following error:

  $ git push
  fatal: You are not currently on a branch.
  To push the history leading to the current (detached HEAD)
  state now, use

    git push ram HEAD:<name-of-remote-branch>

This error is not unique to upstream or simple: current cannot push with
a detached HEAD either.  So, factor out the error string in preparation
for using it in current.

Signed-off-by: Ramkumar Ramachandra <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: artagnon

builtin/push.c

@@ -113,17 +113,19 @@ static NORETURN int die_push_simple(struct branch *branch, struct remote *remote
 	    remote->name, branch->name, advice_maybe);
 }
 
+static const char message_detached_head_die[] =
+	N_("You are not currently on a branch.\n"
+	   "To push the history leading to the current (detached HEAD)\n"
+	   "state now, use\n"
+	   "\n"
+	   "    git push %s HEAD:<name-of-remote-branch>\n");
+
 static void setup_push_upstream(struct remote *remote, int simple)
 {
 	struct strbuf refspec = STRBUF_INIT;
 	struct branch *branch = branch_get(NULL);
 	if (!branch)
-		die(_("You are not currently on a branch.\n"
-		    "To push the history leading to the current (detached HEAD)\n"
-		    "state now, use\n"
-		    "\n"
-		    "    git push %s HEAD:<name-of-remote-branch>\n"),
-		    remote->name);
+		die(_(message_detached_head_die), remote->name);
 	if (!branch->merge_nr || !branch->merge || !branch->remote_name)
 		die(_("The current branch %s has no upstream branch.\n"
 		    "To push the current branch and set the remote as upstream, use\n"