Fix local CSR lookup

Summary:
From what I can tell, `idb file pull` seems to behave slightly differently for simulators. When pulling from a remote simulator, it appears to first create a directory for the local destination causing the read in line 508 to as it is trying to read the *folder* `app.csr` not `app.csr/app.csr`.

By omitting the destination file name, we avoid this behaviour.

Reviewed By: fabiomassimo

Differential Revision: D30541778

fbshipit-source-id: 851398aed5fd350a68ba0686707ce0f0aa09672c

desktop/app/src/server/utils/CertificateProvider.tsx

@@ -489,13 +489,7 @@ export default class CertificateProvider {
     return tmpDir({unsafeCleanup: true})
       .then((dir) => {
         return iosUtil
-          .pull(
-            deviceId,
-            originalFile,
-            bundleId,
-            path.join(dir, csrFileName),
-            this.config.idbPath,
-          )
+          .pull(deviceId, originalFile, bundleId, dir, this.config.idbPath)
           .then(() => dir);
       })
       .then((dir) => {
@@ -512,6 +506,7 @@ export default class CertificateProvider {
           })
           .then((fileName) => {
             const copiedFile = path.resolve(dir, fileName);
+            console.debug('Trying to read CSR from', copiedFile);
             return fs
               .readFile(copiedFile)
               .then((data) => this.santitizeString(data.toString()));