OS X: try cheap ascii .lower() in normcase before making full unicode dance
This is similar to what is done in encoding.lower, introduced in
c481761033bd.
This has been seen making 'hg up' and 'hg st' in a 50000+ files repo 13%
faster.
This might make Mercurial slightly slower for users who mainly use non-ASCII
filenames. That is a reasonable trade-off.
run-tests.py: inherit PYTHONHASHSEED from environment if set
This makes it possible to fix the seed by using for instance
PYTHONHASHSEED=7 ./run-tests.py ...
This can be very convenient when trying to debug problems that are influenced
by hash values. Try different seed values until you find one that triggers the
bad behaviour and then keep that while debugging.
The value 0 will restore default Python behavior and disable randomization.