histedit: create transaction outside of try
Just a little refactoring to simplify the next patch.
Differential Revision: https://phab.mercurial-scm.org/D65
# See http://EditorConfig.org for the specificationroot = true[*.py]indent_size = 4indent_style = spacetrim_trailing_whitespace = true[*.{c,h}]indent_size = 8indent_style = tabtrim_trailing_whitespace = true