Fix reopening the blame view from the main view

* Update %(ref) when opening the blame view from the main view.

* Rework 683fdc8 to set %(file) only
  when opening the blob view and bring back %(file_old).

NEWS.adoc

@@ -9,6 +9,7 @@ Bug fixes:
  - Fix `stat-*` coloring file names in `tig status` instead of just
    markers (regression in 2.5.9). (#1326)
  - Fix keybinding with +[cmd] not triggering view refreshing. (#1324)
+ - Fix reopening the blame view from the main view.
 
 tig-2.5.9
 ---------

src/blame.c

@@ -128,7 +128,7 @@ blame_open(struct view *view, enum open_flags flags)
 
 	if (!view->env->file[0] && opt_file_args && !opt_file_args[1]) {
 		const char *ls_tree_argv[] = {
-			"git", "ls-tree", "-d", "-z", *view->env->ref ? view->env->ref : view->env->commit, opt_file_args[0], NULL
+			"git", "ls-tree", "-d", "-z", *view->env->ref ? view->env->ref : "HEAD", opt_file_args[0], NULL
 		};
 		char buf[SIZEOF_STR] = "";
 
@@ -457,6 +457,10 @@ blame_request(struct view *view, enum request request, struct line *line)
 		open_main_view(view, OPEN_RELOAD);
 		break;
 
+	case REQ_VIEW_BLOB:
+		string_ncopy(view->env->file, blame->commit->filename, strlen(blame->commit->filename));
+		return request;
+
 	default:
 		return request;
 	}
@@ -482,7 +486,10 @@ blame_select(struct view *view, struct line *line)
 		string_format(view->ref, "%s changed %s", commit->id, commit->filename);
 	}
 
-	string_ncopy(view->env->file, commit->filename, strlen(commit->filename));
+	if (strcmp(commit->filename, view->env->file))
+		string_format(view->env->file_old, "%s", commit->filename);
+	else
+		view->env->file_old[0] = '\0';
 
 	view->env->lineno = view->pos.lineno + 1;
 	string_ncopy(view->env->text, text, strlen(text));

src/main.c

@@ -548,6 +548,7 @@ main_request(struct view *view, enum request request, struct line *line)
 				  line->type == LINE_STAT_STAGED ||
 				  line->type == LINE_STAT_UNTRACKED))
 				? OPEN_SPLIT : OPEN_DEFAULT;
+	struct commit *commit = line->data;
 
 	switch (request) {
 	case REQ_VIEW_DIFF:
@@ -576,6 +577,13 @@ main_request(struct view *view, enum request request, struct line *line)
 			return request;
 		break;
 
+	case REQ_VIEW_BLAME:
+		if (string_rev_is_null(commit->id))
+			view->env->ref[0] = 0;
+		else
+			string_copy_rev(view->env->ref, commit->id);
+		return request;
+
 	case REQ_REFRESH:
 		load_refs(true);
 		refresh_view(view);