Fix cover option for ebook

lib/generate/ebook/index.js

@@ -29,14 +29,14 @@ Generator.prototype.finish = function() {
     .then(function() {
         var d = Q.defer();
 
-        var _options = {
-            "--cover": that.options.cover
-        };
-
         if (!that.options.cover && fs.existsSync(path.join(that.options.output, "cover.jpg"))) {
             that.options.cover = path.join(that.options.output, "cover.jpg");
         }
 
+        var _options = {
+            "--cover": that.options.cover
+        };
+
         var command = [
             "ebook-convert",
             path.join(that.options.output, "index.html"),
@@ -51,6 +51,8 @@ Generator.prototype.finish = function() {
             .join(" ")
         ].join(" ");
 
+        console.log(command);
+
         exec(command, function (error, stdout, stderr) {
             if (error) {
                 if (error.code == 127) {