Remove PYTHONPATH requirement to execute run_slave.py.

slave/run_slave.py

Index: slave/run_slave.py
diff --git a/slave/run_slave.py b/slave/run_slave.py
index 27c26e3ef8d46d5794c3e72a8b9118d0a35a3d81..1d1652eff09eb8037c137e218788e57effd2304e 100644
--- a/slave/run_slave.py
+++ b/slave/run_slave.py
@@ -163,8 +163,14 @@ def main():
   else:
     raise NotImplementedError('Unknown platform')
 
-  # Run the slave.
+  # Make sure the path is ok before loading buildbot and twisted.
+  sys.path.append(os.path.join('..', 'third_party', 'buildbot_7_12'))

[nsylvain, 2010/11/05 01:24:00]

The reason why it was in makefile is that we could have created a "make
start_bbot8.2" or "run_slave_8_2.bat".

Now you are pretty much forcing us to fork run_slave.py instead, which is going
to be messy once we start having half the masters using one version, and half
the masters using another version.

[M-A Ruel, 2010/11/05 01:51:58]

My plan is to switch all the slaves to 0.8.2 but keep the masters at 0.7.12 and
slowly switch the masters to 0.8.2.

Disagree?

+  sys.path.append(os.path.join('..', 'third_party', 'twisted_8_1'))
+
+  # Reboot the computer when the master tells the slave to terminate.
   HotPatchSlaveBuilder()
+
+  # Run the slave.
   import twisted.scripts.twistd as twistd
   twistd.run()