[tools] Add a tool to make a no-op change

I used something like this when testing reno 2.5.0.  It's clearly a work
in progress but I figure we could all fix/test it rather than me having
another half implemented tool

Change-Id: I2fa844f4cf8dd7e5c06461b7f7926a7cf84515c3

tools/README.txt

@@ -51,6 +51,13 @@ integration.sh
 
 Used in the gate!  Install all the "$PROJECTS" to verify that g-r and the each project are compatible
 
+noop-change.sh
+--------------
+
+Generate a bulk no-op changes in supplied projects.  Useful if we have a risky
+change in global-requirements or upper-constraints and we want to test impacted
+projects.
+
 publish_constraints.sh
 ----------------------
 Used in the gate!  Generate the constraints files from git for publishing to a

tools/noop-change.sh

@@ -0,0 +1,170 @@
+#!/usr/bin/env bash
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+function cleanup {
+    # Don't abort early if there's a problem in the clean up
+    set +e
+    git checkout $start_branch
+    git branch -D ${topic}
+}
+
+function usage {
+    (
+    if [ -n "$1" ] ; then
+        echo $0 $1
+    fi
+    echo $0 '-p [project] -t [topic] -c [change] -s [style]'
+    echo ' project: The directory for the openstack project'
+    echo ' topic  : The topic as passed to git review'
+    echo ' change : The change that the no-op change depends on if any'
+    echo ' style  : the style of change [doc|python|releasenotes]'
+    ) >&2
+    exit 1
+}
+
+project=''
+topic=''
+change=''
+style=''
+verbose=0
+
+while getopts vp:t:c:s: opt ; do
+    case $opt in
+    p)
+        project=${OPTARG/=}
+    ;;
+    t)
+        topic=${OPTARG/=}
+    ;;
+    c)
+        change=${OPTARG/=}
+    ;;
+    s)
+        style=${OPTARG/=}
+    ;;
+    v)
+        verbose=$((verbose + 1))
+    ;;
+    \?)
+        usage
+    ;;
+    esac
+done
+
+if [ -z "$project" ] ; then
+    usage 'project missing!'
+fi
+
+if [ -z "$topic" ] ; then
+    usage 'topic missing!'
+# NOTE(tonyb): if the topic without white space or / == itself then it didn't
+#              contain any bad characters
+elif [ "${topic/[ 	\/]/}" != "${topic}" ] ; then
+    echo "topic [$topic] contains white space or /'s"
+    exit 1
+fi
+
+# TODO(tonyb): Do we need to validate that change looks like a change ID?
+#             With zuulv3 it could infact be a url or anything so it'd be
+#             hard to validate
+
+if [ -z "$style" ] ; then
+    usage 'style missing!'
+elif [[ ! 'releasenotes doc python' =~ "$style" ]] ; then
+    usage "style $style invalid"
+fi
+
+if [ $verbose -ge 1 ] ; then
+    printf '%-10s: %s\n' 'Project' "$project"
+    printf '%-10s: %s\n' 'Topic' "$topic"
+    printf '%-10s: %s\n' 'Change' "$change"
+    printf '%-10s: %s\n' 'Style' "$style"
+    printf '%-10s: %s\n' 'Verbosity' "$verbose"
+fi
+
+[ $verbose -ge 2 ] && set -x
+
+cd $project
+
+# FIXME(tonyb): Save the current branch
+start_branch=$(git rev-parse --symbolic --abbrev-ref HEAD)
+if [ "$start_branch" == "$topic" ] ; then
+    echo $0 Current git branch is the same as topic aborting >&2
+    exit 1
+fi
+
+# NOTE(tonyb): git diff exits with 0 if the tree is clean
+if ! git diff --exit-code -s ; then
+    echo $0 Current working tree is dirty aborting >&2
+    exit 1
+fi
+
+# The real works starts here so now lets get a bit careful and exit if a
+# command fails
+set -e
+
+git branch -D ${topic} || true
+# NOTE(tonyb): We don't really need to switch branches we could do it all in
+#              the current branch but this is easier.
+git checkout -b ${topic} -t origin/master
+
+# Install the clean up handler
+trap cleanup EXIT
+
+case "$style" in
+releasenotes|doc)
+    file="${style}/source/index.rst"
+    [ "$verbose" -ge 3 ] && git diff
+    echo -e '\n\n.. # no-op test' >> $file
+    git add $file
+;;
+python)
+    # TODO(tonyb): work out a 99% safe way to modify python code
+    echo $0 python syle change isn\'t finished
+    # NOTE(tonyb): The pipeline works like:
+    # Find all the __init__.py files that contain something.
+    #   We know this has to be code of some sort or they'd file pep8.
+    # Remove tests
+    #   Tests might trick the gate into using a subset of jobs
+    # Sort by the 3rd path element.
+    #  project/dir/__init__.py this will mean that paths that don't have a
+    #  dir component will sort to the top.  This (I hope) means that we'll
+    #  prefer the project __init__.py if it exists
+    # Grab only the first item
+    #  We could store this in an array and do something smarter if we wanted
+    file=$(find * -type f -name __init__.py -not -empty | \
+                grep -v tests | \
+                sort -t / -k+3 |\
+                head -n 1)
+    if [ -n "$file" ] ; then
+        echo -e '\n\n# no-op test' >> ${file}
+        [ "$verbose" -ge 3 ] && git diff
+        git add $file
+    else
+        echo $0 failed to find file to patch for $style
+        exit 1
+    fi
+;;
+esac
+
+commit_msg="WiP: Do not merge - $topic"
+if [ -n "$change" ] ; then
+    commit_msg+="
+
+Depends-On: $change"
+fi
+
+git commit -m "$commit_msg"
+git review -t ${topic}
+# TODO(tonyb): Check for vote-a-tron and -W the change if it's available