dispatch: do not close stdout and stderr, just flush() instead
Since 3a4c0905f357 "util: always force line buffered stdout when stdout is
a tty", we have two file objects attached to the same STDOUT_FILENO. If one
is closed, the underlying file descriptor is also closed, and writing to
the other file object would crash the Python interpreter in a hard way, at
least on Windows.
So, it seems safer to not close the standard streams. This also matches
the behavior of the default sys.stdout/stderr.close(), which never close
the FILE* streams in C layer.
https://hg.python.org/cpython/file/v2.7.13/Python/sysmodule.c#l1401
#require execbit
$ hg init
$ echo a > a
$ hg ci -Am'not executable'
adding a
$ chmod +x a
$ hg ci -m'executable'
$ hg id
79abf14474dc tip
Make sure we notice the change of mode if the cached size == -1:
$ hg rm a
$ hg revert -r 0 a
$ hg debugstate
n 0 -1 unset a
$ hg status
M a
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg id
d69afc33ff8a
$ test -x a && echo executable -- bad || echo not executable -- good
not executable -- good