Splitting trychange for git_try and removing no longer needed support for:

git_try.py

Index: git_try.py
diff --git a/git_try.py b/git_try.py
index f8f6d306a86c921032090ca45dbdc37780bd2dd9..f6f4ae2e5aa2acdd45a00da106c6b963a24aa77f 100755
--- a/git_try.py
+++ b/git_try.py
@@ -12,7 +12,7 @@ import breakpad  # pylint: disable=W0611
 from scm import GIT
 import subprocess2
 import third_party.upload
-import trychange
+import trychange_git
 import git_cl
 
 
@@ -53,12 +53,10 @@ def main(args):
     if rietveld_url:
       args.extend(['--rietveld_url', GetRietveldServerUrl()])
   try:
-    cl = git_cl.Changelist()
-    change = cl.GetChange(cl.GetUpstreamBranch(), None)
     # Hack around a limitation in logging.
     logging.getLogger().handlers = []
-    sys.exit(trychange.TryChange(
-        args, change, swallow_exception=False,
+    sys.exit(trychange_git.TryChange_Git(
+        args, swallow_exception=False,
         prog='git try',
         extra_epilog='\n'
                      'git try will diff against your tracked branch and will '