add check for change in newRepoString (#198)

Add a check if newRepo string is different from the currentRepo string

Previously, the phaseService would always be called to change the
repository if the newRepoString is a valid repo.

Let's first check if the newRepoString is different from the currentRepo
before calling the phaseService to changeRepository.

src/app/shared/layout/header.component.ts

@@ -212,6 +212,9 @@ export class HeaderComponent implements OnInit {
    * Change repository viewed on Issue Dashboard, if a valid repository is provided.
    */
   changeRepositoryIfValid(repo: Repo, newRepoString: string) {
+    if (newRepoString === this.currentRepo) {
+      return;
+    }
     this.phaseService
       .changeRepositoryIfValid(repo)
       .then(() => {