As "expected", the patch doesn't work: it randomize the output order :-(

I checked "sparc Ubuntu 3.x": the output order is correct. "test_xxx" lines are written to stdout, "FAIL: ..." + traceback are written to stderr, and the lines are written in the right order.

But it failed on "x86 Tiger 3.x" :
http://www.python.org/dev/buildbot/3.x/builders/x86 Tiger 3.x/builds/130/steps/test/logs/stdio
http://www.python.org/dev/buildbot/3.x/builders/x86 Tiger 3.x/builds/131/steps/test/logs/stdio

When a test is reexecuted in verbose mode, the output is written in red (why not, but it was not the case before my commit), and the stdout and stderr are in a "mixed".

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antoine> just output the traceback more carefully.

Encode the traceback by hand would be possible, but it's more complex. A possible solution would be to write the output to a StringIO, encode unicode to bytes using the right encoding and backslashreplace error handler, and write the result to stdout. But I don't like buffering the output because the buildbot may hung for different reasons (search in the bug tracker for "test_multiprocessing" or "test_subprocess"...) and the buildbot master may consider the buildbot as dead (no new output since xxx seconds, whereas it's writing to a buffer).

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I prefer my first simple idea: use backslashreplace error handler for stdout. Let's try: r80703. This commit reverts my previous commit, apply regrtest_stdout_backslashreplace.patch + a fix for multiprocessing mode (regrtest.py -j ...).