Bug 265030

I originally thought this is what Bug 261789 was about, but that actually says "I want to make a PR just for the most recent commit", and the errors from check-webkit-style are therefore incidental there.

We seemingly are passing the output from git-format-patch (an mbox) into the DiffParser, and unsurprisingly passing something that isn't a diff into the DiffParser fails:

To use the example from the other bug:

OpenSource % git webkit pr  --no-commit
ERROR: Unexpected diff format when parsing a chunk: 'From 7ba7f1664729c24f8bb6f7a24bda5a64b71b2deb Mon Sep 17 00:00:00 2001'
ERROR: Unexpected diff format when parsing a chunk: 'From: Simon Fraser <simon.fraser@apple.com>'
ERROR: Unexpected diff format when parsing a chunk: 'Date: Tue, 19 Sep 2023 17:45:18 -0700'
ERROR: Unexpected diff format when parsing a chunk: 'Subject: [PATCH 2/2] Add UnifiedPDF feature flag, PDFPluginBase.* and fix the'
ERROR: Unexpected diff format when parsing a chunk: 'Reviewed by NOBODY (OOPS!).'
ERROR: Unexpected diff format when parsing a chunk: 'Add a feature flag for UnifiedPDF, which is a PDF plugin shared between platforms.'
ERROR: Unexpected diff format when parsing a chunk: 'Add empty PDFPluginBase.h/mm files, and deal with the unified sources fallout.'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/SourcesCocoa.txt:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebKit.xcodeproj/project.pbxproj:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/Plugins/PDF/PDFPluginBase.h: Copied from Source/WebKit/WebProcess/WebCoreSupport/WebBadgeClient.cpp.'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/Plugins/PDF/PDFPluginBase.mm: Copied from Source/WebKit/WebProcess/WebCoreSupport/WebBadgeClient.cpp.'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/WebCoreSupport/WebBadgeClient.cpp:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/WebCoreSupport/mac/WebContextMenuClientMac.mm:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/WebPage/Cocoa/WebPageCocoa.mm:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteScrollbarsController.h:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteScrollbarsController.mm:'
ERROR: Unexpected diff format when parsing a chunk: '(WebKit::RemoteScrollbarsController::shouldRegisterScrollbars const):'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/webpushd/MockPushServiceConnection.mm:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/webpushd/PushService.mm:'
ERROR: Unexpected diff format when parsing a chunk: '* Source/WebKit/webpushd/PushServiceConnection.mm:'

The bug here is that we're passing the output of git-format-patch, rather than git-diff.