Use consistent Cache-Tag format

modules/actions/serveJavaScriptModule.js

@@ -16,7 +16,7 @@ function serveJavaScriptModule(req, res) {
         'Content-Type': getContentTypeHeader(req.entry.contentType),
         'Cache-Control': 'public, max-age=31536000, immutable', // 1 year
         ETag: etag(code),
-        'Cache-Tag': 'file,js-file,js-module'
+        'Cache-Tag': 'file, js-file, js-module'
       })
       .send(code);
   } catch (error) {

modules/actions/serveStaticFile.js

@@ -18,7 +18,7 @@ function serveStaticFile(req, res) {
       'Cache-Control': 'public, max-age=31536000, immutable', // 1 year
       'Last-Modified': req.entry.lastModified,
       ETag: etag(req.entry.content),
-      'Cache-Tag': tags.join(',')
+      'Cache-Tag': tags.join(', ')
     })
     .send(req.entry.content);
 }

modules/middleware/fetchPackage.js

@@ -13,7 +13,7 @@ function tagRedirect(req, res) {
   res
     .set({
       'Cache-Control': 'public, max-age=60',
-      'Cache-Tag': 'redirect,tag-redirect'
+      'Cache-Tag': 'redirect, tag-redirect'
     })
     .redirect(
       302,
@@ -32,7 +32,7 @@ function semverRedirect(req, res) {
     res
       .set({
         'Cache-Control': 'public, max-age=60',
-        'Cache-Tag': 'redirect,semver-redirect'
+        'Cache-Tag': 'redirect, semver-redirect'
       })
       .redirect(
         302,