hgweb: fix empty navigation detection For some obscure reason, changelog.node(0) returns nullid if changelog is empty. this break empty navigation detection. We fix this code by using the length of the changelog. Using the length have some issue with revision filtering but this is a small step in the right direction. Proper fix comes in later changeset.

tests: AIX can't handle negative date in test-dirstate.t test-dirstate.t fails on AIX in the absurd date test. AIX touch errors on any date prior to 1970. AIX mktime() gives an error on such dates, so the problem is deeper than touch and attempts to work around touch in Python failed. Give up. Add an AIX test to hghave and skip the absurd date test on AIX.

win32: use explicit path to "python.exe" only if it exists Before this patch, "hg.bat" for Windows environment always uses "%~dp0..\python" as explicit path to "python.exe". This path may not be valid in some cases. For example, on the environment using "virtualenv" python package, both "python.exe" and "hg.bat" are placed in the same directory. In this case, "python.exe" should be found on PATH, because virtualenv activation script puts "python.exe" on the PATH. This patch uses explicit path to "python.exe" only if it exists, and expects that "python.exe" can be found on PATH otherwise.