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

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

Index: sdk/lib/_internal/pub/lib/src/log.dart
diff --git a/sdk/lib/_internal/pub/lib/src/log.dart b/sdk/lib/_internal/pub/lib/src/log.dart
index 14627122e29b4eb1d3faec6ed8d03cb045d6124b..1f5956a6c983dc60b9a31b141701a293416a9758 100644
--- a/sdk/lib/_internal/pub/lib/src/log.dart
+++ b/sdk/lib/_internal/pub/lib/src/log.dart
@@ -42,9 +42,6 @@ const _MAX_TRANSCRIPT = 10000;
 /// [recordTranscript()] is called.
 Transcript<Entry> _transcript;
 
-/// All currently-running progress indicators.
-final _progresses = new Set<Progress>();
-
 /// The currently-animated progress indicator, if any.
 ///
 /// This will also be in [_progresses].
@@ -374,13 +371,10 @@ void dumpTranscript() {
 /// information will only be visible at [Level.FINE].
 Future progress(String message, Future callback(), {bool fine: false}) {
   _stopProgress();
+
   var progress = new Progress(message, fine: fine);
   _animatedProgress = progress;
-  _progresses.add(progress);
-  return callback().whenComplete(() {
-    progress.stop();
-    _progresses.remove(progress);
-  });
+  return callback().whenComplete(progress.stop);
 }
 
 /// Stops animating the running progress indicator, if currently running.
@@ -389,6 +383,30 @@ void _stopProgress() {
   _animatedProgress = null;
 }
 
+/// The number of outstanding calls to [muteProgress] that have not been unmuted
+/// yet.
+int _numMutes = 0;
+
+/// Whether progress animation should be muted or not.
+bool get isMuted => _numMutes > 0;
+
+/// Stops animating any ongoing progress.
+///
+/// This is called before spawning Git since Git sometimes writes directly to
+/// the terminal to ask for login credentials, which would then get overwritten
+/// by the progress animation.
+///
+/// Each call to this must be paired with a call to [unmuteProgress].
+void muteProgress() {
+  _numMutes++;
+}
+
+/// Resumes animating any ongoing progress once all calls to [muteProgress]
+/// have made their matching [unmuteProgress].
+void unmuteProgress() {
+  _numMutes--;

[Jacob, 2015/01/08 23:46:25]

nit:
consider adding

assert(_numMutes > 0); 

[Bob Nystrom, 2015/01/08 23:58:19]

Done.

+}
+
 /// Wraps [text] in the ANSI escape codes to make it bold when on a platform
 /// that supports that.
 ///