Allow a commit message to be specified to merge-to-branch.sh

tools/common-includes.sh

 # 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
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 59 matching lines @@
       die "Can't continue. Please delete branch $1 and try again."
     fi
   fi
 }
 
 # Persist and restore variables to support canceling/resuming execution
 # of this script.
 persist() {
   local VARNAME=$1
   local FILE="$PERSISTFILE_BASENAME-$VARNAME"
-  echo "${!VARNAME}" > $FILE
+  local VALUE="${!VARNAME}"
+  if [ -z "$VALUE" ] ; then
+    VALUE="__EMPTY__"
+  fi
+  echo "$VALUE" > $FILE
 }
 
 restore() {
   local VARNAME=$1
   local FILE="$PERSISTFILE_BASENAME-$VARNAME"
   local VALUE="$(cat $FILE)"

[Sven Panne, 2012/03/28 11:40:39]

I'm just curious: Why is this detour via __EMPTY__ necessary? The echo/cat combo
seems to do the right thing even for empty strings, but probably I'm missing
something...

+  [[ -z "$VALUE" ]] && die "Variable '$VARNAME' could not be restored."
+  if [ "$VALUE" == "__EMPTY__" ] ; then
+    VALUE=""
+  fi
   eval "$VARNAME=\"$VALUE\""
 }
 
 restore_if_unset() {
   local VARNAME=$1
   [[ -z "${!VARNAME}" ]] && restore "$VARNAME"
-  [[ -z "${!VARNAME}" ]] && die "Variable '$VARNAME' could not be restored."
 }
 
 initial_environment_checks() {
   # Cancel if this is not a git checkout.
   [[ -d .git ]] \
     || die "This is not a git checkout, this script won't work for you."
 
   # Cancel if EDITOR is unset or not executable.
   [[ -n "$EDITOR" && -x "$(which $EDITOR)" ]] \
     || die "Please set your EDITOR environment variable, you'll need it."
@@ skipping 84 matching lines @@
     git add "$FILE"
   done
   # Stage deleted files.
   DELETED_FILES=$(git status -s -uno --porcelain | grep "^ D" \
                                                  | awk '{print $NF}')
   for FILE in $DELETED_FILES ; do
     git rm "$FILE"
   done
   rm -f "$TOUCHED_FILES_FILE"
 }