A few more fixes for testing in the repo.

lib/src/io.dart

Index: lib/src/io.dart
diff --git a/lib/src/io.dart b/lib/src/io.dart
index 46ae81a1cea90ae7f2315952402407bb8c8caf93..7fcfcc360b58ffa9c20a5706d75cd5ac2755be28 100644
--- a/lib/src/io.dart
+++ b/lib/src/io.dart
@@ -496,7 +496,13 @@ final bool runningFromSdk =
 /// A regular expression to match the script path of a pub script running from
 /// source in the Dart repo.
 final _dartRepoRegExp = new RegExp(
-    r"/third_party/pkg_tested/pub/(bin/pub.dart|test/.*_test\.dart)$");
+    r"/third_party/pkg_tested/pub/("
+            r"bin/pub\.dart"
+        r"|"
+            r"\.pub/pub\.test\.snapshot"
+        r"|"
+            r"test/.*_test\.dart"
+        r")$");
 
 /// Whether pub is running from source in the Dart repo.
 ///