gulp.js

function bumpVersion(bumpType) {
    return function () {
        var version = null;

        gulp.src('./package.json')
            .pipe(bump({type: bumpType}))
            .pipe(gulp.dest('./'))
            .pipe(tap(function (file) {
                version = JSON.parse(String(file.contents)).version;
                process.stdout.write('version ' + version); // correct version here
            }))
            .pipe(git.commit("Bump package version: " + version)) // but null here
            .pipe(git.tag("v" + version, 'Version message', function (err) { // and here
                if (err) throw err;
            }));
    }
}