Use python3 urllib when urllib2 not available

This is part of a series of changes to introduce Python3 support.

Change-Id: I605b145791053c1f2d7bf3c907c5a68649b21d12
diff --git a/git_config.py b/git_config.py
index d6510aa..6589b19 100644
--- a/git_config.py
+++ b/git_config.py
@@ -23,7 +23,18 @@
 except ImportError:
   import dummy_threading as _threading
 import time
-import urllib2
+try:
+  import urllib2
+except ImportError:
+  # For python3
+  import urllib.request
+  import urllib.error
+else:
+  # For python2
+  import imp
+  urllib = imp.new_module('urllib')
+  urllib.request = urllib2
+  urllib.error = urllib2
 
 from signal import SIGTERM
 from error import GitError, UploadError
@@ -580,7 +591,7 @@
       else:
         try:
           info_url = u + 'ssh_info'
-          info = urllib2.urlopen(info_url).read()
+          info = urllib.request.urlopen(info_url).read()
           if '<' in info:
             # Assume the server gave us some sort of HTML
             # response back, like maybe a login page.
@@ -593,9 +604,9 @@
           else:
             host, port = info.split()
             self._review_url = self._SshReviewUrl(userEmail, host, port)
-        except urllib2.HTTPError as e:
+        except urllib.error.HTTPError as e:
           raise UploadError('%s: %s' % (self.review, str(e)))
-        except urllib2.URLError as e:
+        except urllib.error.URLError as e:
           raise UploadError('%s: %s' % (self.review, str(e)))
 
         REVIEW_CACHE[u] = self._review_url
diff --git a/main.py b/main.py
index 7a09c6b..10e1cf8 100755
--- a/main.py
+++ b/main.py
@@ -29,7 +29,16 @@
 import os
 import sys
 import time
-import urllib2
+try:
+  import urllib2
+except ImportError:
+  # For python3
+  import urllib.request
+else:
+  # For python2
+  import imp
+  urllib = imp.new_module('urllib')
+  urllib.request = urllib2
 
 from trace import SetTrace
 from git_command import git, GitCommand
@@ -267,7 +276,7 @@
       py_version[0], py_version[1], py_version[2])
   return _user_agent
 
-class _UserAgentHandler(urllib2.BaseHandler):
+class _UserAgentHandler(urllib.request.BaseHandler):
   def http_request(self, req):
     req.add_header('User-Agent', _UserAgent())
     return req
@@ -289,10 +298,10 @@
         return
       handler.passwd.add_password(None, url, user, password)
 
-class _BasicAuthHandler(urllib2.HTTPBasicAuthHandler):
+class _BasicAuthHandler(urllib.request.HTTPBasicAuthHandler):
   def http_error_401(self, req, fp, code, msg, headers):
     _AddPasswordFromUserInput(self, msg, req)
-    return urllib2.HTTPBasicAuthHandler.http_error_401(
+    return urllib.request.HTTPBasicAuthHandler.http_error_401(
       self, req, fp, code, msg, headers)
 
   def http_error_auth_reqed(self, authreq, host, req, headers):
@@ -302,7 +311,7 @@
         val = val.replace('\n', '')
         old_add_header(name, val)
       req.add_header = _add_header
-      return urllib2.AbstractBasicAuthHandler.http_error_auth_reqed(
+      return urllib.request.AbstractBasicAuthHandler.http_error_auth_reqed(
         self, authreq, host, req, headers)
     except:
       reset = getattr(self, 'reset_retry_count', None)
@@ -312,10 +321,10 @@
         self.retried = 0
       raise
 
-class _DigestAuthHandler(urllib2.HTTPDigestAuthHandler):
+class _DigestAuthHandler(urllib.request.HTTPDigestAuthHandler):
   def http_error_401(self, req, fp, code, msg, headers):
     _AddPasswordFromUserInput(self, msg, req)
-    return urllib2.HTTPDigestAuthHandler.http_error_401(
+    return urllib.request.HTTPDigestAuthHandler.http_error_401(
       self, req, fp, code, msg, headers)
 
   def http_error_auth_reqed(self, auth_header, host, req, headers):
@@ -325,7 +334,7 @@
         val = val.replace('\n', '')
         old_add_header(name, val)
       req.add_header = _add_header
-      return urllib2.AbstractDigestAuthHandler.http_error_auth_reqed(
+      return urllib.request.AbstractDigestAuthHandler.http_error_auth_reqed(
         self, auth_header, host, req, headers)
     except:
       reset = getattr(self, 'reset_retry_count', None)
@@ -338,7 +347,7 @@
 def init_http():
   handlers = [_UserAgentHandler()]
 
-  mgr = urllib2.HTTPPasswordMgrWithDefaultRealm()
+  mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()
   try:
     n = netrc.netrc()
     for host in n.hosts:
@@ -354,11 +363,11 @@
 
   if 'http_proxy' in os.environ:
     url = os.environ['http_proxy']
-    handlers.append(urllib2.ProxyHandler({'http': url, 'https': url}))
+    handlers.append(urllib.request.ProxyHandler({'http': url, 'https': url}))
   if 'REPO_CURL_VERBOSE' in os.environ:
-    handlers.append(urllib2.HTTPHandler(debuglevel=1))
-    handlers.append(urllib2.HTTPSHandler(debuglevel=1))
-  urllib2.install_opener(urllib2.build_opener(*handlers))
+    handlers.append(urllib.request.HTTPHandler(debuglevel=1))
+    handlers.append(urllib.request.HTTPSHandler(debuglevel=1))
+  urllib.request.install_opener(urllib.request.build_opener(*handlers))
 
 def _Main(argv):
   result = 0
diff --git a/repo b/repo
index 7c633fc..060ea6d 100755
--- a/repo
+++ b/repo
@@ -122,7 +122,18 @@
 import re
 import subprocess
 import sys
-import urllib2
+try:
+  import urllib2
+except ImportError:
+  # For python3
+  import urllib.request
+  import urllib.error
+else:
+  # For python2
+  import imp
+  urllib = imp.new_module('urllib')
+  urllib.request = urllib2
+  urllib.error = urllib2
 
 home_dot_repo = os.path.expanduser('~/.repoconfig')
 gpg_dir = os.path.join(home_dot_repo, 'gnupg')
@@ -355,7 +366,7 @@
 def _InitHttp():
   handlers = []
 
-  mgr = urllib2.HTTPPasswordMgrWithDefaultRealm()
+  mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()
   try:
     import netrc
     n = netrc.netrc()
@@ -365,16 +376,16 @@
       mgr.add_password(p[1], 'https://%s/' % host, p[0], p[2])
   except:
     pass
-  handlers.append(urllib2.HTTPBasicAuthHandler(mgr))
-  handlers.append(urllib2.HTTPDigestAuthHandler(mgr))
+  handlers.append(urllib.request.HTTPBasicAuthHandler(mgr))
+  handlers.append(urllib.request.HTTPDigestAuthHandler(mgr))
 
   if 'http_proxy' in os.environ:
     url = os.environ['http_proxy']
-    handlers.append(urllib2.ProxyHandler({'http': url, 'https': url}))
+    handlers.append(urllib.request.ProxyHandler({'http': url, 'https': url}))
   if 'REPO_CURL_VERBOSE' in os.environ:
-    handlers.append(urllib2.HTTPHandler(debuglevel=1))
-    handlers.append(urllib2.HTTPSHandler(debuglevel=1))
-  urllib2.install_opener(urllib2.build_opener(*handlers))
+    handlers.append(urllib.request.HTTPHandler(debuglevel=1))
+    handlers.append(urllib.request.HTTPSHandler(debuglevel=1))
+  urllib.request.install_opener(urllib.request.build_opener(*handlers))
 
 def _Fetch(url, local, src, quiet):
   if not quiet:
@@ -423,14 +434,14 @@
   dest = open(os.path.join(local, '.git', 'clone.bundle'), 'w+b')
   try:
     try:
-      r = urllib2.urlopen(url)
-    except urllib2.HTTPError as e:
+      r = urllib.request.urlopen(url)
+    except urllib.error.HTTPError as e:
       if e.code == 404:
         return False
       print >>sys.stderr, 'fatal: Cannot get %s' % url
       print >>sys.stderr, 'fatal: HTTP error %s' % e.code
       raise CloneFailure()
-    except urllib2.URLError as e:
+    except urllib.error.URLError as e:
       print >>sys.stderr, 'fatal: Cannot get %s' % url
       print >>sys.stderr, 'fatal: error %s' % e.reason
       raise CloneFailure()