Overriding -documentForURL: to use +gitDirForURL: to convert incoming URLs to the .git dir before checking for an open document, so that open a repository from subdirectories won’t open duplicate windows.

PBRepositoryDocumentController.m

@@ -7,7 +7,7 @@
 //
 
 #import "PBRepositoryDocumentController.h"
-
+#import "PBGitRepository.h"
 
 @implementation PBRepositoryDocumentController
 // This method is overridden to configure the open panel to only allow
@@ -18,4 +18,10 @@
 	[openPanel setCanChooseDirectories:YES];
 	return [openPanel runModalForDirectory:nil file:nil types:nil];
 }
+
+// Convert paths to the .git dir before searching for an already open document
+- (id)documentForURL:(NSURL *)URL
+{
+	return [super documentForURL:[PBGitRepository gitDirForURL:URL]];
+}
 @end