Python script as server-side for AngularJS app on IIS7

I have directive to display player image. I send player id to small Python script to check if image with such id exists via ajax call. If image exists, I need to return its name.

I succeeded in sending id from fronted to script and finding the image name. The problem is that I am failing to return the file name correctly. I am getting error:

HTTP Error 502.2 - Bad Gateway The specified CGI application misbehaved by not returning a complete set of HTTP headers. The headers it did return are "HCP_23108_SmithKen.png ".

If I add headers, I am still getting error:

HTTP Error 502.2 - Bad Gateway The specified CGI application misbehaved by not returning a complete set of HTTP headers. The headers it did return are "Content-type: text/html; charset=utf-8 HCP_23108_SmithKen.png ".

I did enabled cgi in Handler Mappings of IIS7 by following Python on IIS: how?

My question is how to perform Ajax GET request correctly without any Python frameworks? Thanks

Directives:

myDirectives.directive('headshot', function ($http) {

return {
    restrict: 'AE',
    scope: {
        lastProID: '@lastproid'
    },
    template: '<img ng-src="{{proImg}}" class="headshot">',
    link: function (scope, element, attrs) {

        //scope.id = scope.lastProID;
        attrs.$observe('lastproid', function (id) {

            scope.id = id;
            var src = 'img/bios/nophoto.png';
            scope.proImg = (src);


            var url = 'bioPhoto/bioPhoto.py';
            $http.get(
                    url,
                    {
                        params: {'id': scope.id}
                    })

                    .success(function (data) {
                        var src = 'img/bios/' + data;
                        scope.proImg = (src);
                    })
                    .error(function (error) {
                    });
        });
    }
};
});

bioPhoto.py script:

import fnmatch
import os

rootPath = './img/bios/'

query_string=os.environ["QUERY_STRING"]
id=query_string.split("id=",1)[1]
id=id.strip()

pattern = "*" + id + "*"

print ('Content-type: text/html; charset=utf-8')

for root, dirs, files in os.walk(rootPath):
    for filename in fnmatch.filter(files, pattern):
        filename=filename.strip()
        print(filename)