util: debugstacktrace, flush before and after writing Close another stream (default stdout, which often is buffered) before writing to the primary stream (default stderr, which often is unbuffered). The primary stream is also flushed after writing (in case it is buffered). This fixes non-deterministic output order, especially on windows.

run-tests.py: work when --with-hg is set to system hg Previously we'd always assume that --with-hg is a script in a user directory, and would write out a 'python' symlink to the same location. That didn't work if --with-hg was set to a system installation of hg, e.g. /usr/bin/hg. Introduce a TMPBINDIR directory which is used to write out the python symlink.