perf: omit copying from ui.ferr to ui.fout for Mercurial earlier than 1.9
Before this patch, referring ui.ferr prevents perf.py from measuring
performance with Mercurial earlier than 1.9 (or 4e1ccd4c2b6d), because
ui.ferr isn't available in such Mercurial, even though there are some
code paths for Mercurial earlier than 1.9 in perf.py.
For example, setting "_prereadsize" attribute in perfindex() and
perfnodelookup() is effective only with hg earlier than 1.8 (or
61c9bc3da402).
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true