run-tests.py: pass --install-scripts to setup.py

This avoids possible problems when the user has a ~/.pydistutils.cfg.
Fixes issue638.  Patch provided by Ralf Schmitt.

tests/run-tests.py

@@ -136,8 +136,9 b' def install_hg():'
 
     os.chdir("..") # Get back to hg root
     cmd = ('%s setup.py clean --all'
-           ' install --force --home="%s" --install-lib="%s" >%s 2>&1'
-           % (sys.executable, INST, PYTHONDIR, installerrs))
+           ' install --force --home="%s" --install-lib="%s"'
+           ' --install-scripts="%s" >%s 2>&1'
+           % (sys.executable, INST, PYTHONDIR, BINDIR, installerrs))
     vlog("# Running", cmd)
     if os.system(cmd) == 0:
         if not verbose: