[PATCH 2 of 3 V2] revsetbenchmark: automatically finds the perf extension

[pierre-yves.david at ens-lyon.org]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at fb.com>
# Date 1398802702 25200
#      Tue Apr 29 13:18:22 2014 -0700
# Node ID ecfe676f25f7c02f7eae88496de1adebb258f822
# Parent  d8a52ce003ac21569dae2023ecc648e7769bdb54
revsetbenchmark: automatically finds the perf extension

Before this changeset, you had to stand in the root of the mercurial repo to run
the `revsetbenchmark.py` script. Otherwise, the perf extension would not be
found a `./contrib/perf.py` and the script would crash in panic.

We now figure out the contrib directory from the location of this script. This
makes it possible to run the script from other location that the mercurial repo
root (but you still need to be in the core mercurial repository)

diff --git a/contrib/revsetbenchmarks.py b/contrib/revsetbenchmarks.py
--- a/contrib/revsetbenchmarks.py
+++ b/contrib/revsetbenchmarks.py
@@ -12,10 +12,11 @@
 #
 # This script also does one run of the current version of mercurial installed
 # to compare performance.
 
 import sys
+import os
 from subprocess import check_call, Popen, CalledProcessError, STDOUT, PIPE
 # cannot use argparse, python 2.7 only
 from optparse import OptionParser
 
 
@@ -40,11 +41,12 @@ def update(rev):
 def perf(revset):
     """run benchmark for this very revset"""
     try:
         output = check_output(['./hg',
                                '--config',
-                               'extensions.perf=contrib/perf.py',
+                               'extensions.perf='
+                               + os.path.join(contribdir, 'perf.py'),
                                'perfrevset',
                                revset],
                                stderr=STDOUT)
         output = output.lstrip('!') # remove useless ! in this context
         return output.strip()
@@ -77,10 +79,11 @@ parser.add_option("-f", "--file",
 
 if len(sys.argv) < 2:
     parser.print_help()
     sys.exit(255)
 
+contribdir = os.path.dirname(sys.argv[0])
 
 target_rev = args[0]
 
 revsetsfile = sys.stdin
 if options.file: