Steps to reproduce: 1. Import changesets from <https://hg.mozilla.org/try/rev/2d4d022a4a7251bf6598f23ba2f0619676d0f656> 2. Run `hg rebase -k -b . -d 138f65958545` Actual result: $ hg rebase -k -b . -d 138f65958545 rebasing 502778:3abcfaa0a77a "Bug 1411609 - Remove nsIChannel::AsyncOpen. r?mcmanus" file 'netwerk/base/nsSecCheckWrapChannel.cpp' was deleted in other [source] but was modified in local [dest]. What do you want to do? use (c)hanged version, (d)elete, or leave (u)nresolved? d file 'netwerk/base/nsSecCheckWrapChannel.h' was deleted in other [source] but was modified in local [dest]. What do you want to do? use (c)hanged version, (d)elete, or leave (u)nresolved? d merging dom/ipc/TabParent.cpp merging dom/jsurl/nsJSProtocolHandler.cpp merging image/decoders/icon/win/nsIconChannel.cpp merging modules/libjar/nsJARChannel.cpp merging modules/libjar/nsJARChannel.h merging netwerk/base/SimpleChannel.cpp merging netwerk/base/nsBaseChannel.cpp merging netwerk/base/nsBaseChannel.h merging netwerk/base/nsIOService.cpp merging netwerk/base/nsNetUtil.cpp merging netwerk/protocol/about/nsAboutCache.cpp merging netwerk/protocol/about/nsAboutCache.h merging netwerk/protocol/data/DataChannelChild.cpp merging netwerk/protocol/file/FileChannelChild.cpp merging netwerk/protocol/ftp/FTPChannelChild.cpp merging netwerk/protocol/ftp/FTPChannelChild.h merging netwerk/protocol/ftp/FTPChannelParent.cpp merging netwerk/protocol/http/HttpBaseChannel.cpp merging netwerk/protocol/http/HttpBaseChannel.h merging netwerk/protocol/http/HttpChannelChild.cpp merging netwerk/protocol/http/HttpChannelChild.h merging netwerk/protocol/http/HttpChannelParent.cpp merging netwerk/protocol/http/InterceptedHttpChannel.cpp merging netwerk/protocol/http/InterceptedHttpChannel.h merging netwerk/protocol/http/NullHttpChannel.cpp merging netwerk/protocol/http/TrackingDummyChannel.cpp merging netwerk/protocol/http/nsHttpChannel.cpp merging netwerk/protocol/http/nsHttpChannel.h merging netwerk/protocol/res/ExtensionProtocolHandler.cpp merging netwerk/protocol/viewsource/nsViewSourceChannel.cpp merging netwerk/protocol/wyciwyg/WyciwygChannelChild.cpp merging netwerk/protocol/wyciwyg/WyciwygChannelChild.h merging netwerk/protocol/wyciwyg/WyciwygChannelParent.cpp merging netwerk/protocol/wyciwyg/nsWyciwygChannel.cpp merging netwerk/protocol/wyciwyg/nsWyciwygChannel.h merging netwerk/streamconv/converters/nsMultiMixedConv.cpp merging uriloader/exthandler/ExternalHelperAppParent.cpp merging uriloader/exthandler/nsExternalProtocolHandler.cpp rebasing 502779:d9790a93fec0 "Bug 1325897 - Unship some Universal CRT DLLs. r?glandium" rebasing 502780:62f6afb9120a "Disable remote XUL in tests" rebasing 502781:9498bfba7583 "1342659_utf8_download" merging xpcom/io/FileDescriptorFile.cpp merging xpcom/io/nsLocalFileUnix.cpp merging xpcom/io/nsLocalFileUnix.h merging xpcom/io/nsLocalFileWin.cpp merging xpcom/io/nsLocalFileWin.h rebasing 502782:24667320d17c "Stop enabling followsymlinks" merging dom/base/StructuredCloneHolder.cpp merging dom/events/DataTransferItem.cpp merging dom/file/FileCreatorHelper.cpp merging dom/filesystem/Directory.cpp merging dom/filesystem/FileSystemBase.cpp merging dom/filesystem/GetDirectoryListingTask.cpp merging dom/filesystem/GetFileOrDirectoryTask.cpp merging dom/filesystem/GetFilesHelper.cpp merging dom/filesystem/GetFilesTask.cpp merging dom/html/HTMLInputElement.cpp merging dom/plugins/base/nsPluginDirServiceProvider.cpp merging dom/plugins/ipc/PluginModuleChild.cpp merging extensions/spellcheck/hunspell/glue/mozHunspell.cpp merging js/xpconnect/src/XPCShellImpl.cpp merging layout/forms/nsFileControlFrame.cpp merging modules/libpref/Preferences.cpp merging netwerk/protocol/file/nsFileChannel.cpp merging toolkit/components/startup/nsAppStartup.cpp merging toolkit/profile/nsToolkitProfileService.cpp merging toolkit/xre/nsAppRunner.cpp merging toolkit/xre/nsXREDirProvider.cpp merging uriloader/exthandler/nsExternalHelperAppService.cpp merging uriloader/exthandler/win/nsMIMEInfoWin.cpp merging widget/nsFilePickerProxy.cpp merging widget/windows/JumpListBuilder.cpp merging widget/windows/nsClipboard.cpp merging xpcom/base/nsCycleCollector.cpp merging xpcom/build/BinaryPath.h merging xpcom/build/nsXPCOM.h merging xpcom/io/SpecialSystemDirectory.cpp merging xpcom/io/nsAppFileLocationProvider.cpp merging xpcom/io/nsLocalFileWin.cpp rebasing 502783:8cf5c5e386e4 "Templatize aFollowLinks" merging xpcom/build/nsXPCOM.h merging xpcom/io/nsLocalFileWin.cpp note: rebase of 502783:8cf5c5e386e4 created no changes to commit rebasing 502784:f4c18240fa8c "Bug 1365199 - Add an enablePrivilege specific pref and use it in Talos. r?jmaher" merging js/xpconnect/src/xpcpublic.h merging js/xpconnect/wrappers/WrapperFactory.cpp rebasing 502785:666f85b8f3ca "Bug 1433179 - Add ReferrerUrl and HostUrl to the Zone.Information stream. r=Paolo" rebasing 502786:cfd9c38f19b0 "Bug 1484186 - Remove broken addon check from WidgetEvent::PreventDefault(). r=masayuki" merging widget/WidgetEventImpl.cpp rebasing 502787:5050d50399b3 "rm_success_codes" Changeset 502783:8cf5c5e386e4 has been lost even though it actually has changes to commit. Expected result: All changesets should be rebased successfully.

Rebasing the attached patch set from 4a3f88e36298 to 08e30fbc9ab1 in my case dropped *all* changed .cpp/.h files: > $ hg pull central && hg rebase -s base -d central > pulling from central > searching for changes > no changes found > rebasing 449239:1fb6f5e795b4 "Bug 1478776 - Part 1: Define Visual Viewport event handlers. r?botond" > merging dom/base/VisualViewport.h > rebasing 449240:bf9d4be4863a "Bug 1478776 - Part 2: Initial Visual Viewport event infrastructure. r?botond" > merging dom/base/VisualViewport.cpp > merging dom/base/VisualViewport.h > merging layout/base/PresShell.cpp > merging layout/base/nsIPresShell.h > merging layout/base/nsRefreshDriver.cpp > merging layout/base/nsRefreshDriver.h > note: rebase of 449240:bf9d4be4863a created no changes to commit > rebasing 449241:9b221a251f07 "Bug 1478776 - Part 3: Add an event flag for dispatching to system group only. r?smaug" > merging dom/events/EventDispatcher.cpp > merging widget/BasicEvents.h > note: rebase of 449241:9b221a251f07 created no changes to commit > rebasing 449242:c05de1a32363 "Bug 1478776 - Part 4: Define internal VisualViewport resize/scroll events. r?botond" > merging dom/base/VisualViewport.cpp > merging dom/base/VisualViewport.h > merging dom/events/EventNameList.h > merging widget/BasicEvents.h > merging widget/EventMessageList.h > rebasing 449243:07d49ee7d2bb "SS debug logging" > rebasing 449244:cfa9d6de02d5 "debug: test new events in mobile session store" > rebasing 449245:ca98371cade1 "Bug 1498812 - Part n: Allow registering System event listeners through nsSessionStoreUtils. r?" > merging toolkit/components/sessionstore/nsSessionStoreUtils.cpp > rebasing 449246:e6c2b5abda14 "desktop ss test" (visualscroll) I'm using the changes from bug 1511594 comment 7 in my mercurial.ini, too, in order to work around bug 1511594.

Can you please confirm that you have the latest vcs? You can do this by going ‘Mach bootstra’

Yes, I executed `./mach bootstrap` again and agin during the test. If same files are modified multiple times in the commit series, format-source would not presreve the change correctly.

This is because of the workaround from bug 151194. I will close this since this is just a side effect of the mentioned bug.