Mute progress animation while Git is running so it doesn't overwrite credential prompts.

sdk/lib/_internal/pub/lib/src/git.dart

Index: sdk/lib/_internal/pub/lib/src/git.dart
diff --git a/sdk/lib/_internal/pub/lib/src/git.dart b/sdk/lib/_internal/pub/lib/src/git.dart
index 2c522eb09a816a47860a3c6d1ef2757085a44fa0..53d69d89f3d6012776888d85db5beea3a0148a17 100644
--- a/sdk/lib/_internal/pub/lib/src/git.dart
+++ b/sdk/lib/_internal/pub/lib/src/git.dart
@@ -50,10 +50,14 @@ Future<List<String>> run(List<String> args,
         "Please ensure Git is correctly installed.");
   }
 
+  log.muteProgress();
   return runProcess(_gitCommand, args, workingDir: workingDir,
       environment: environment).then((result) {
     if (!result.success) throw new GitException(args, result.stderr.join("\n"));
+
     return result.stdout;
+  }).whenComplete(() {
+    log.unmuteProgress();
   });
 }