Properly detect if git revisions aren't in a git repository.

sdk/lib/_internal/pub_generated/lib/src/source/git.dart

Index: sdk/lib/_internal/pub_generated/lib/src/source/git.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/source/git.dart b/sdk/lib/_internal/pub_generated/lib/src/source/git.dart
index abf8125b3155af12ac842e061b37744e2a33c7cd..d4a6af3874575f6f58a635168f16f7fdbfd64822 100644
--- a/sdk/lib/_internal/pub_generated/lib/src/source/git.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/source/git.dart
@@ -272,26 +272,30 @@ class GitSource extends CachedSource {
   Future<String> _ensureRevision(PackageId id) {
     return new Future.sync(() {
       var path = _repoCachePath(id);
+      log.fine("ensuring $path has ${id.description}");
       if (!entryExists(path)) {
-        return _clone(
-            _getUrl(id),
-            path,
-            mirror: true).then((_) => _revParse(id));
+        log.fine("$path doesn't exist");
+        return _clone(_getUrl(id), path, mirror: true).then((_) => _getRev(id));
       }
 
       // If [id] didn't come from a lockfile, it may be using a symbolic
       // reference. We want to get the latest version of that reference.
       var description = id.description;
       if (description is! Map || !description.containsKey('resolved-ref')) {
-        return _updateRepoCache(id).then((_) => _revParse(id));
+        log.fine("ID doesn't have a resolved ref");
+        return _updateRepoCache(id).then((_) => _getRev(id));
       }
 
       // If [id] did come from a lockfile, then we want to avoid running "git
       // fetch" if possible to avoid networking time and errors. See if the
       // revision exists in the repo cache before updating it.
-      return _revParse(id).catchError((error) {
+      return _getRev(id).then((res) {
+        log.fine("ref is $res");
+        return res;
+      }).catchError((error) {
+        log.fine("repo doesn't have ref, updating");
         if (error is! git.GitException) throw error;
-        return _updateRepoCache(id).then((_) => _revParse(id));
+        return _updateRepoCache(id).then((_) => _getRev(id));
       });
     });
   }
@@ -308,13 +312,13 @@ class GitSource extends CachedSource {
     });
   }
 
-  /// Runs "git rev-parse" in the canonical clone of the repository referred to
+  /// Runs "git rev-list" in the canonical clone of the repository referred to
   /// by [id] on the effective ref of [id].
   ///
   /// This assumes that the canonical clone already exists.
-  Future<String> _revParse(PackageId id) {
+  Future<String> _getRev(PackageId id) {
     return git.run(
-        ["rev-parse", _getEffectiveRef(id)],
+        ["rev-list", "--max-count=1", _getEffectiveRef(id)],
         workingDir: _repoCachePath(id)).then((result) => result.first);
   }