stdio: raise StdioError if something goes wrong in ui.flush
The prior code used to ignore all errors, which was intended to
deal with a decade-old problem with writing to broken pipes on
Windows.
However, that code inadvertantly went a lot further, making it
impossible to detect *all* I/O errors on stdio ... but only sometimes.
What actually happened was that if Mercurial wrote less than a stdio
buffer's worth of output (the overwhelmingly common case for most
commands), any error that occurred would get swallowed here. But
if the buffering strategy changed, an unhandled IOError could be
raised from any number of other locations.
Because we now have a top-level StdioError handler, and ui._write
and ui._write_err (and now flush!) will raise that exception, we
have one rational place to detect and handle these errors.
Mercurial
=========
Mercurial is a fast, easy to use, distributed revision control tool
for software developers.
Basic install:
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing:
$ make local # build for inplace usage
$ ./hg --version # should show the latest version
See https://mercurial-scm.org/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.