rebase: add support to keep branch names
Callback on extra fields added by Patrick Mezard <pmezard@gmail.com>.
default = 'changelog'
mimetype = 'text/xml; charset={encoding}'
header = header.tmpl
changelog = changelog.tmpl
changelogentry = changelogentry.tmpl
filelog = filelog.tmpl
filelogentry = filelogentry.tmpl
tags = tags.tmpl
tagentry = tagentry.tmpl