Properly handle Git URLs with trailing slashes.

utils/pub/git_source.dart

Index: utils/pub/git_source.dart
diff --git a/utils/pub/git_source.dart b/utils/pub/git_source.dart
index 7f59d8941e9a15b578e2cd6bc6d9fd3ba9cda2ba..a815feb2c7638dc47abaaf70223c5cb4524fb957 100644
--- a/utils/pub/git_source.dart
+++ b/utils/pub/git_source.dart
@@ -64,8 +64,10 @@ class GitSource extends Source {
    * The package name of a Git repo is the name of the directory into which
    * it'll be cloned.
    */
-  String packageName(description) =>
-    basename(_getUrl(description)).replaceFirst(const RegExp("\.git\$"), "");
+  String packageName(description) {
+    return basename(_getUrl(description)
+        .replaceFirst(const RegExp(@"(\.git)?/?$"), ""));
+  }
 
   /**
    * Ensures [description] is a Git URL.