nodetree: simplify a conditionnal in shortesthexnodeidprefix instead of try to catch some attribute error, we could just nicely look if the attribute will be available. This make the code simpler to follow and less error prone since we no longer rely on a wider attribute catching. Differential Revision: https://phab.mercurial-scm.org/D7651

config: close file even if we fail to read it If we get an exception from cfg.read(), we would not close the file before this patch. This patch uses a context manager to make sure we close it. Differential Revision: https://phab.mercurial-scm.org/D7626

config: catch intended exception when failing to parse config When a new config parser was introduced in fca54469480e (ui: introduce new config parser, 2009-04-23), the reading side would raise a ConfigError which was then caught in the ui code. Then, in 2123aad24d56 (error: add new ParseError for various parsing errors, 2010-06-04), a ParseError was raised instead, but the call site was not updated. Let's start catching that ParseError. We still don't print it in a friendly way, but that's not worse than before. Differential Revision: https://phab.mercurial-scm.org/D7625