Setup git-svn and handle detached HEAD state in auto-rebaseline script.

Tools/Scripts/webkitpy/tool/commands/rebaseline.py

Index: Tools/Scripts/webkitpy/tool/commands/rebaseline.py
diff --git a/Tools/Scripts/webkitpy/tool/commands/rebaseline.py b/Tools/Scripts/webkitpy/tool/commands/rebaseline.py
index 9d238f4fd3dc3ddf7a1f0b28a1d2f54fd2eedd30..1c35f2389417bb36e80110ee4869954b48ca756e 100644
--- a/Tools/Scripts/webkitpy/tool/commands/rebaseline.py
+++ b/Tools/Scripts/webkitpy/tool/commands/rebaseline.py
@@ -803,6 +803,9 @@ class AutoRebaseline(AbstractParallelRebaselineCommand):
             _log.error("Cannot proceed with working directory changes. Clean working directory first.")
             return
 
+        # Setup git-svn for dcommit.
+        tool.executive.run_command(['git', 'auto-svn'])

[Dirk Pranke, 2015/06/12 19:51:30]

I wonder if there's much of a cost to running this every time, and if we should
only run this if svn isn't set up.

[joelo, 2015/06/17 18:37:37]

Good point, done.

+
         revision_data = self.bot_revision_data()
         if not revision_data:
             return
@@ -829,7 +832,10 @@ class AutoRebaseline(AbstractParallelRebaselineCommand):
 
         did_finish = False
         try:
-            old_branch_name = tool.scm().current_branch()
+            old_branch_name = tool.executive.run_command(["git", "rev-parse", "--symbolic-full-name", "HEAD"])
+            if old_branch_name == "HEAD":
+                # If HEAD is detached use commit SHA instead.
+                old_branch_name = tool.executive.run_command(["git", "rev-parse", "HEAD"])
             tool.scm().delete_branch(self.AUTO_REBASELINE_BRANCH_NAME)
             tool.scm().create_clean_branch(self.AUTO_REBASELINE_BRANCH_NAME)