Python 3 updates to build script

These updates should allow the build_osd.py script to work with
Python 3.x and is based on changes made in the similar script in
the USD distribution.

build_scripts/build_osd.py

@@ -21,14 +21,18 @@
 # KIND, either express or implied. See the Apache License for the specific
 # language governing permissions and limitations under the Apache License.
 #
+from __future__ import print_function
+
 from distutils.spawn import find_executable
 
 import argparse
+import codecs
 import contextlib
 import datetime
 import distutils
 import fnmatch
 import glob
+import locale
 import multiprocessing
 import os
 import platform
@@ -38,34 +42,41 @@ import shutil
 import subprocess
 import sys
 import tarfile
-import urllib2
 import zipfile
 
+if sys.version_info.major >= 3:
+    from urllib.request import urlopen
+else:
+    from urllib2 import urlopen
+
 # Helpers for printing output
 verbosity = 1
 
 def Print(msg):
     if verbosity > 0:
-        print msg
+        print(msg)
 
 def PrintWarning(warning):
     if verbosity > 0:
-        print "WARNING:", warning
+        print("WARNING:", warning)
 
 def PrintStatus(status):
     if verbosity >= 1:
-        print "STATUS:", status
+        print("STATUS:", status)
 
 def PrintInfo(info):
     if verbosity >= 2:
-        print "INFO:", info
+        print("INFO:", info)
 
 def PrintCommandOutput(output):
     if verbosity >= 3:
         sys.stdout.write(output)
 
 def PrintError(error):
-    print "ERROR:", error
+    if verbosity >= 3 and sys.exc_info()[1] is not None:
+        import traceback
+        traceback.print_exc()
+    print("ERROR:", error)
 
 # Helpers for determining platform
 def Windows():
@@ -75,11 +86,15 @@ def Linux():
 def MacOS():
     return platform.system() == "Darwin"
 
+def GetLocale():
+    return sys.stdout.encoding or locale.getdefaultlocale()[1] or "UTF-8"
+
 def GetCommandOutput(command):
     """Executes the specified command and returns output or None."""
     try:
         return subprocess.check_output(
-            shlex.split(command), stderr=subprocess.STDOUT).strip()
+            shlex.split(command),
+            stderr=subprocess.STDOUT).decode(GetLocale(), 'replace').strip()
     except subprocess.CalledProcessError:
         pass
     return None
@@ -136,7 +151,7 @@ def Run(cmd, logCommandOutput = True):
     """Run the specified command in a subprocess."""
     PrintInfo('Running "{cmd}"'.format(cmd=cmd))
 
-    with open("log.txt", "a") as logfile:
+    with codecs.open("log.txt", "a", "utf-8") as logfile:
         logfile.write(datetime.datetime.now().strftime("%Y-%m-%d %H:%M"))
         logfile.write("\n")
         logfile.write(cmd)
@@ -148,8 +163,8 @@ def Run(cmd, logCommandOutput = True):
             p = subprocess.Popen(shlex.split(cmd), stdout=subprocess.PIPE,
                                  stderr=subprocess.STDOUT)
             while True:
-                l = p.stdout.readline()
-                if l != "":
+                l = p.stdout.readline().decode(GetLocale(), 'replace')
+                if l:
                     logfile.write(l)
                     PrintCommandOutput(l)
                 elif p.poll() is not None:
@@ -305,7 +320,7 @@ def DownloadFileWithPowershell(url, outputFilename):
     Run(cmd,logCommandOutput=False)
 
 def DownloadFileWithUrllib(url, outputFilename):
-    r = urllib2.urlopen(url)
+    r = urlopen(url)
     with open(outputFilename, "wb") as outfile:
         outfile.write(r.read())
 
@@ -344,7 +359,7 @@ def DownloadURL(url, context, force, dontExtract = None):
             if os.path.exists(tmpFilename):
                 os.remove(tmpFilename)
 
-            for i in xrange(maxRetries):
+            for i in range(maxRetries):
                 try:
                     context.downloader(url, tmpFilename)
                     break
@@ -975,7 +990,7 @@ if context.buildArgs:
 
 def FormatBuildArguments(buildArgs):
     s = ""
-    for depName in sorted(buildArgs.iterkeys()):
+    for depName in sorted(buildArgs.keys()):
         args = buildArgs[depName]
         s += """
                                 {name}: {args}""".format(