Add -R option to merge-to-branch script to revert from bleeding_edge.

tools/merge-to-branch.sh

 #!/bin/bash
 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
@@ skipping 51 matching lines @@
   source $COMMIT_HASHES_FILE
 }
 
 restore_patch_commit_hashes_if_unset() {
   [[ "${#PATCH_COMMIT_HASHES[@]}" == 0 ]] && restore_patch_commit_hashes
   [[ "${#PATCH_COMMIT_HASHES[@]}" == 0 ]] && [[ -z "$EXTRA_PATCH" ]] && \
       die "Variable PATCH_COMMIT_HASHES could not be restored."
 }
 
 ########## Option parsing
+REVERT_FROM_BLEEDING_EDGE=0
 
-while getopts ":hs:fp:rm:" OPTION ; do
+while getopts ":hs:fp:rm:R" OPTION ; do
   case $OPTION in
     h)  usage
         exit 0
         ;;
     p)  EXTRA_PATCH=$OPTARG
         ;;
     f)  rm -f "$ALREADY_MERGING_SENTINEL_FILE"
         ;;
     r)  REVERSE_PATCH="--reverse"
         ;;
     m)  NEW_COMMIT_MSG=$OPTARG
         ;;
     s)  START_STEP=$OPTARG
         ;;
+    R)  REVERSE_PATCH="--reverse"
+        REVERT_FROM_BLEEDING_EDGE=1
+        ;;
     ?)  echo "Illegal option: -$OPTARG"
         usage
         exit 1
         ;;
   esac
 done
 let OPTION_COUNT=$OPTIND-1
 shift $OPTION_COUNT
 
 ########## Regular workflow
 
 # If there is a merge in progress, abort.
 [[ -e "$ALREADY_MERGING_SENTINEL_FILE" ]] && [[ $START_STEP -eq 0 ]] \
    && die "A merge is already in progress"
 touch "$ALREADY_MERGING_SENTINEL_FILE"
 
 initial_environment_checks
 
 if [ $START_STEP -le $CURRENT_STEP ] ; then
-  if [ ${#@} -lt 2 ] ; then
+  let MIN_EXPECTED_ARGS=2-$REVERT_FROM_BLEEDING_EDGE
+  if [ ${#@} -lt $MIN_EXPECTED_ARGS ] ; then
     if [ -z "$EXTRA_PATCH" ] ; then
       die "Either a patch file or revision numbers must be specified"
     fi
     if [ -z "$NEW_COMMIT_MSG" ] ; then
       die "You must specify a merge comment if no patches are specified"
     fi
   fi
   echo ">>> Step $CURRENT_STEP: Preparation"
-  MERGE_TO_BRANCH=$1
-  [[ -n "$MERGE_TO_BRANCH" ]] || die "Please specify a branch to merge to"
-  shift
+  if [ $REVERT_FROM_BLEEDING_EDGE==1 ] ; then
+    MERGE_TO_BRANCH="bleeding_edge"
+  else
+    MERGE_TO_BRANCH=$1
+    [[ -n "$MERGE_TO_BRANCH" ]] || die "Please specify a branch to merge to"
+    shift
+  fi
   persist "MERGE_TO_BRANCH"
   common_prepare
 fi
 
 let CURRENT_STEP+=1
 if [ $START_STEP -le $CURRENT_STEP ] ; then
   echo ">>> Step $CURRENT_STEP: Create a fresh branch for the patch."
   restore_if_unset "MERGE_TO_BRANCH"
   git checkout -b $BRANCHNAME svn/$MERGE_TO_BRANCH \
     || die "Creating branch $BRANCHNAME failed."
 fi
 
 let CURRENT_STEP+=1
 if [ $START_STEP -le $CURRENT_STEP ] ; then
   echo ">>> Step $CURRENT_STEP: Find the git \
 revisions associated with the patches."
   current=0
   for REVISION in "$@" ; do
     NEXT_HASH=$(git svn find-rev "r$REVISION" svn/bleeding_edge)
     [[ -n "$NEXT_HASH" ]] \
       || die "Cannot determine git hash for r$REVISION"
     PATCH_COMMIT_HASHES[$current]="$NEXT_HASH"
     [[ -n "$REVISION_LIST" ]] && REVISION_LIST="$REVISION_LIST,"
     REVISION_LIST="$REVISION_LIST r$REVISION"
     let current+=1
   done
   if [ -n "$REVISION_LIST" ] ; then
     if [ -n "$REVERSE_PATCH" ] ; then
-      NEW_COMMIT_MSG="Rollback of$REVISION_LIST in $MERGE_TO_BRANCH branch."
+      if [ $REVERT_FROM_BLEEDING_EDGE -eq 0 ] ; then
+        NEW_COMMIT_MSG="Rollback of$REVISION_LIST in $MERGE_TO_BRANCH branch."
+      else
+        NEW_COMMIT_MSG="Revert$REVISION_LIST."
+      fi
     else
       NEW_COMMIT_MSG="Merged$REVISION_LIST into $MERGE_TO_BRANCH branch."
     fi;
   fi;
 
   echo "$NEW_COMMIT_MSG" > $COMMITMSG_FILE
   echo "" >> $COMMITMSG_FILE
   for HASH in ${PATCH_COMMIT_HASHES[@]} ; do
     PATCH_MERGE_DESCRIPTION=$(git log -1 --format=%s $HASH)
     echo "$PATCH_MERGE_DESCRIPTION" >> $COMMITMSG_FILE
@@ skipping 24 matching lines @@
     echo "Applying patch for $HASH to $MERGE_TO_BRANCH..."
     git log -1 -p $HASH > "$TEMPORARY_PATCH_FILE"
     apply_patch "$TEMPORARY_PATCH_FILE"
   done
   if [ -n "$EXTRA_PATCH" ] ; then
     apply_patch "$EXTRA_PATCH"
   fi
 fi
 
 let CURRENT_STEP+=1
-if [ $START_STEP -le $CURRENT_STEP ] ; then
+if [ $START_STEP -le $CURRENT_STEP ] && [ $REVERT_FROM_BLEEDING_EDGE -eq 0 ] ; then
   echo ">>> Step $CURRENT_STEP: Prepare $VERSION_FILE."
   # These version numbers are used again for creating the tag
   read_and_persist_version
 fi
 
 let CURRENT_STEP+=1
-if [ $START_STEP -le $CURRENT_STEP ] ; then
+if [ $START_STEP -le $CURRENT_STEP ] && [ $REVERT_FROM_BLEEDING_EDGE -eq 0 ] ; then
   echo ">>> Step $CURRENT_STEP: Increment version number."
   restore_if_unset "PATCH"
   NEWPATCH=$(($PATCH + 1))
   confirm "Automatically increment PATCH_LEVEL? (Saying 'n' will fire up \
 your EDITOR on $VERSION_FILE so you can make arbitrary changes. When \
 you're done, save the file and exit your EDITOR.)"
   if [ $? -eq 0 ] ; then
     echo $NEWPATCH $VERSION_FILE
     sed -e "/#define PATCH_LEVEL/s/[0-9]*$/$NEWPATCH/" \
         -i.bak "$VERSION_FILE" || die "Could not increment patch level"
@@ skipping 17 matching lines @@
   echo ">>> Step $CURRENT_STEP: Commit to the repository."
   restore_if_unset "MERGE_TO_BRANCH"
   git checkout $BRANCHNAME \
     || die "cannot ensure that the current branch is $BRANCHNAME"
   wait_for_lgtm
   PRESUBMIT_TREE_CHECK="skip" git cl dcommit \
     || die "failed to commit to $MERGE_TO_BRANCH"
 fi
 
 let CURRENT_STEP+=1
-if [ $START_STEP -le $CURRENT_STEP ] ; then
+if [ $START_STEP -le $CURRENT_STEP ] && [ $REVERT_FROM_BLEEDING_EDGE -eq 0 ] ; then
   echo ">>> Step $CURRENT_STEP: Determine svn commit revision"
   restore_if_unset "NEW_COMMIT_MSG"
   restore_if_unset "MERGE_TO_BRANCH"
   git svn fetch || die "'git svn fetch' failed."
   COMMIT_HASH=$(git log -1 --format=%H --grep="$NEW_COMMIT_MSG" \
     svn/$MERGE_TO_BRANCH)
   [[ -z "$COMMIT_HASH" ]] && die "Unable to map git commit to svn revision"
   SVN_REVISION=$(git svn find-rev $COMMIT_HASH)
   echo "subversion revision number is r$SVN_REVISION"
   persist "SVN_REVISION"
 fi
 
 let CURRENT_STEP+=1
-if [ $START_STEP -le $CURRENT_STEP ] ; then
+if [ $START_STEP -le $CURRENT_STEP ] && [ $REVERT_FROM_BLEEDING_EDGE -eq 0 ] ; then
   echo ">>> Step $CURRENT_STEP: Create the tag."
   restore_if_unset "SVN_REVISION"
   restore_version_if_unset "NEW"
   echo "Creating tag svn/tags/$NEWMAJOR.$NEWMINOR.$NEWBUILD.$NEWPATCH"
   if [ "$MERGE_TO_BRANCH" == "trunk" ] ; then
     TO_URL="$MERGE_TO_BRANCH"
   else
     TO_URL="branches/$MERGE_TO_BRANCH"
   fi
   svn copy -r $SVN_REVISION \
     https://v8.googlecode.com/svn/$TO_URL \
     https://v8.googlecode.com/svn/tags/$NEWMAJOR.$NEWMINOR.$NEWBUILD.$NEWPATCH \
     -m "Tagging version $NEWMAJOR.$NEWMINOR.$NEWBUILD.$NEWPATCH"
   persist "TO_URL"
 fi
 
 let CURRENT_STEP+=1
 if [ $START_STEP -le $CURRENT_STEP ] ; then
   echo ">>> Step $CURRENT_STEP: Cleanup."
   restore_if_unset "SVN_REVISION"
   restore_if_unset "TO_URL"
   restore_if_unset "REVISION_LIST"
   restore_version_if_unset "NEW"
   common_cleanup
-  echo "*** SUMMARY ***"
-  echo "version: $NEWMAJOR.$NEWMINOR.$NEWBUILD.$NEWPATCH"
-  echo "branch: $TO_URL"
-  echo "svn revision: $SVN_REVISION"
-  [[ -n "$REVISION_LIST" ]] && echo "patches:$REVISION_LIST"
+  if [ $REVERT_FROM_BLEEDING_EDGE==0 ] ; then
+    echo "*** SUMMARY ***"
+    echo "version: $NEWMAJOR.$NEWMINOR.$NEWBUILD.$NEWPATCH"
+    echo "branch: $TO_URL"
+    echo "svn revision: $SVN_REVISION"
+    [[ -n "$REVISION_LIST" ]] && echo "patches:$REVISION_LIST"
+  fi
 fi