Cannot create a buffer called 'remote' if there's already one called
'REMOTE' because win32 is not case-sensitive. When we use as
git-mergetool, there's always buffers called BASE, LOCAL, and REMOTE. So
append a suffix to disambiguate. These buffers are derived by removing
conflicts from the merge file, so I call them _derived.
Fix buffer already exists error on win32.
Cannot create a buffer called 'remote' if there's already one called 'REMOTE' because win32 is not case-sensitive. When we use as git-mergetool, there's always buffers called BASE, LOCAL, and REMOTE. So append a suffix to disambiguate. These buffers are derived by removing conflicts from the merge file, so I call them _derived.