hehe

import os
import shutil
import sys

print('NOTE: Please make sure that you have both a .jpg and a .png of the SAME filename, in the SAME directory. This will NOT work otherwise. Thank you.')

targetImage = input('Target image name: ')
if not targetImage:
    sys.exit()

numChangedFiles = 0

for path, dirs, files in os.walk('.'):
    if 'phase_' in path:
        for f in files:
            file_name, file_extension = os.path.splitext(f)
            if file_extension == '.jpg' or file_extension == '.png':
                path_name = os.path.join(path, f)
                if not targetImage in path_name:
                    os.remove(path_name)
                    shutil.copyfile(targetImage + file_extension, path_name)
                    print('Replaced %s' % path_name)
                    numChangedFiles += 1

print('Replaced %s files.' % numChangedFiles)
print('Done.')