Reset container width when switching to pipelines MR tab

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/29539

app/assets/javascripts/merge_request_tabs.js

@@ -131,12 +131,8 @@ require('./flash');
           offset: 0,
         });
       } else if (action === 'pipelines') {
-        if (this.pipelinesLoaded) {
-          return;
-        }
-        const pipelineTableViewEl = document.querySelector('#commit-pipeline-table-view');
-        gl.commits.pipelines.PipelinesTableBundle.$mount(pipelineTableViewEl);
-        this.pipelinesLoaded = true;
+        this.resetViewContainer();
+        this.loadPipelines();
       } else {
         this.expandView();
         this.resetViewContainer();
@@ -225,6 +221,15 @@ require('./flash');
       });
     }
+    loadPipelines() {
+      if (this.pipelinesLoaded) {
+        return;
+      }
+      const pipelineTableViewEl = document.querySelector('#commit-pipeline-table-view');
+      gl.commits.pipelines.PipelinesTableBundle.$mount(pipelineTableViewEl);
+      this.pipelinesLoaded = true;
+    }
+
     loadDiff(source) {
       if (this.diffsLoaded) {
         return;