Add wrapper module

This takes the wrapper importing code from main.py and moves it into
its own module so that other modules may import it without causing
circular imports with main.py.

Change-Id: I9402950573933ed6f14ce0bfb600f74f32727705

main.py

@@ -46,6 +46,7 @@ from error import NoSuchProjectError
 from error import RepoChangedException
 from manifest_xml import XmlManifest
 from pager import RunPager
+from wrapper import WrapperPath, Wrapper
 
 from subcmds import all_commands
 
@@ -169,21 +170,10 @@ class _Repo(object):
 
     return result
 
+
 def _MyRepoPath():
   return os.path.dirname(__file__)
 
-def _MyWrapperPath():
-  return os.path.join(os.path.dirname(__file__), 'repo')
-
-_wrapper_module = None
-def WrapperModule():
-  global _wrapper_module
-  if not _wrapper_module:
-    _wrapper_module = imp.load_source('wrapper', _MyWrapperPath())
-  return _wrapper_module
-
-def _CurrentWrapperVersion():
-  return WrapperModule().VERSION
 
 def _CheckWrapperVersion(ver, repo_path):
   if not repo_path:
@@ -193,7 +183,7 @@ def _CheckWrapperVersion(ver, repo_path):
     print('no --wrapper-version argument', file=sys.stderr)
     sys.exit(1)
 
-  exp = _CurrentWrapperVersion()
+  exp = Wrapper().VERSION
   ver = tuple(map(int, ver.split('.')))
   if len(ver) == 1:
     ver = (0, ver[0])
@@ -205,7 +195,7 @@ def _CheckWrapperVersion(ver, repo_path):
 !!! You must upgrade before you can continue:   !!!
 
     cp %s %s
-""" % (exp_str, _MyWrapperPath(), repo_path), file=sys.stderr)
+""" % (exp_str, WrapperPath(), repo_path), file=sys.stderr)
     sys.exit(1)
 
   if exp > ver:
@@ -214,7 +204,7 @@ def _CheckWrapperVersion(ver, repo_path):
 ... You should upgrade soon:
 
     cp %s %s
-""" % (exp_str, _MyWrapperPath(), repo_path), file=sys.stderr)
+""" % (exp_str, WrapperPath(), repo_path), file=sys.stderr)
 
 def _CheckRepoDir(repo_dir):
   if not repo_dir: