Changed markdown lexer to ignore lists containing only one item

web/react/utils/markdown.jsx

@@ -289,19 +289,22 @@ class MattermostLexer extends marked.Lexer {
             // list
             cap = this.rules.list.exec(src);
             if (cap) {
-                src = src.substring(cap[0].length);
                 const bull = cap[2];
+                let l = cap[0].length;
+
+                // Get each top-level item.
+                cap = cap[0].match(this.rules.item);
+
+                if (cap.length > 1) {
+                    src = src.substring(l);
 
                     this.tokens.push({
                         type: 'list_start',
                         ordered: bull.length > 1
                     });
 
-                // Get each top-level item.
-                cap = cap[0].match(this.rules.item);
-
                     let next = false;
-                const l = cap.length;
+                    l = cap.length;
 
                     for (let i = 0; i < l; i++) {
                         let item = cap[i];
@@ -358,6 +361,7 @@ class MattermostLexer extends marked.Lexer {
 
                     continue;
                 }
+            }
 
             // html
             cap = this.rules.html.exec(src);