how to prevent usemin from overwriting original index.html file - gruntjs

Question

I'm using usemin and I generally like it, but I really dislike the fact that usemin overwrites my original index.html file. I have a pretty typical setup in my Gruntfile:
useminPrepare: {
html: '<%= yeoman.app %>/index.html',
options: {
root: '<%= yeoman.root %>',
staging: '<%= yeoman.tmp %>',
dest: '<%= yeoman.dist %>',
flow: {
html: {
steps: {
js: ['concat', 'uglifyjs'],
css: ['cssmin']
},
post: {}
}
}
}
},
Whenever I build using grunt everything in the end gets dumped into a dist directory. Most other tasks that need to do 'temporary' modifications copy and modify files in a .tmp directory.
usemin mucks with the actual index.html file though. I particularly don't like this because it makes Github think the file has changed every time I check in new code.
Is there a way to tell usemin to use the .tmp directory like most other grunt plugins?
I do specify my temp directory with:
staging: '<%= yeoman.tmp %>'
but that doesn't seem to prevent the index.html file from being overwritten.
Thanks.
UPDATE (per the comment below)
Here is the usemin task itself:
// Performs rewrites based on filerev and the useminPrepare configuration
usemin: {
html: ['<%= yeoman.dist %>/{,*/}*.html'],
css: ['<%= yeoman.dist %>/styles/{,*/}*.css'],
options: {
assetsDirs: ['<%= yeoman.dist %>','<%= yeoman.dist %>/images']
}
},
and here is the grunt task that uses both useminPrepare and usemin:
grunt.registerTask('build', [
'clean:dist',
'wiredep',
'useminPrepare',
'concurrent:dist',
'autoprefixer',
'concat',
'ngAnnotate',
'copy:dist',
'cdnify',
'cssmin',
'uglify',
'filerev',
'usemin',
'htmlmin',
'bridge:dist'
]);

Answer 1

just do not perform filerev task. This is the task that modify the original html files.