Add a failing test of dynamic imports from user:name packages.

Confirms #8751.

tools/tests/apps/dynamic-import/.meteor/packages

@@ -25,3 +25,4 @@ dispatch:mocha-phantomjs
 dispatch:mocha-browser
 lazy-test-package
 helper-package
+user:colon-name

tools/tests/apps/dynamic-import/packages/colon-name/README.md

@@ -0,0 +1,3 @@
+This package exists to test dynamic imports from packages that are
+prefixed by a username, and thus have a colon between the username and the
+package name.

tools/tests/apps/dynamic-import/packages/colon-name/dynamic.js

@@ -0,0 +1 @@
+export const name = module.id;

tools/tests/apps/dynamic-import/packages/colon-name/package.js

@@ -0,0 +1,12 @@
+Package.describe({
+  name: "user:colon-name",
+  version: "0.0.1",
+  summary: "Package with a colon in its name",
+  git: "https://github.com/meteor/meteor/tree/devel/" +
+    "tools/tests/apps/dynamic-import/packages",
+  documentation: "README.md"
+});
+
+Package.onUse(function(api) {
+  api.use("ecmascript");
+});

tools/tests/apps/dynamic-import/tests.js

@@ -194,6 +194,15 @@ describe("dynamic import(...)", function () {
       assert.deepEqual(m, {});
     });
   });
+
+  it("should work for package names containing colons", () => {
+    import("meteor/user:colon-name/dynamic.js").then(dynamic => {
+      assert.strictEqual(
+        dynamic.name,
+        "/node_modules/meteor/user:colon-name/dynamic.js"
+      );
+    });
+  });
 });
 
 function maybeClearDynamicImportCache() {