MemoryError even trying to scan a empty txt file - ubuntu

Hi i hit MemoryError even scanning a empty .txt file.

OS: ubuntu linux
scancode version 2.2.1
>wget https://github.com/nexB/scancode-toolkit/releases/download/v2.2.1/scancode-toolkit-2.2.1.zip
>unzip

ubuntu@ip-172-xx-xx-xx:~/scancode-toolkit-2.2.1$ ./scancode -f json ./empty.txt > result.json
Scanning files for: licenses, copyrights, packages with 1 process(es)...
Building license detection index...Traceback (most recent call last):
File "/home/ubuntu/scancode-toolkit-2.2.1/bin/scancode", line 11, in
load_entry_point('scancode-toolkit', 'console_scripts', 'scancode')()
File "/home/ubuntu/scancode-toolkit-2.2.1/local/lib/python2.7/site-packages/click/core.py", line 722, in __call__
return self.main(*args, **kwargs)
File "/home/ubuntu/scancode-toolkit-2.2.1/src/scancode/utils.py", line 74, in main
standalone_mode=standalone_mode, **extra)
File "/home/ubuntu/scancode-toolkit-2.2.1/local/lib/python2.7/site-packages/click/core.py", line 697, in main
rv = self.invoke(ctx)
File "/home/ubuntu/scancode-toolkit-2.2.1/local/lib/python2.7/site-packages/click/core.py", line 895, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/ubuntu/scancode-toolkit-2.2.1/local/lib/python2.7/site-packages/click/core.py", line 535, in invoke
return callback(*args, **kwargs)
File "/home/ubuntu/scancode-toolkit-2.2.1/local/lib/python2.7/site-packages/click/decorators.py", line 17, in new_func
return f(get_current_context(), *args, **kwargs)
File "/home/ubuntu/scancode-toolkit-2.2.1/src/scancode/cli.py", line 490, in scancode
pre_scan_plugins=pre_scan_plugins)
File "/home/ubuntu/scancode-toolkit-2.2.1/src/scancode/cli.py", line 572, in scan
get_index(False)
File "/home/ubuntu/scancode-toolkit-2.2.1/src/licensedcode/cache.py", line 188, in get_index
_LICENSES_INDEX = get_or_build_index_through_cache()
File "/home/ubuntu/scancode-toolkit-2.2.1/src/licensedcode/cache.py", line 148, in get_or_build_index_through_cache
ifc.write(idx.dumps())
File "/home/ubuntu/scancode-toolkit-2.2.1/src/licensedcode/index.py", line 653, in dumps
return pickle.dumps(self, protocol=cPickle.HIGHEST_PROTOCOL)
File "/usr/lib/python2.7/pickle.py", line 1380, in dumps
Pickler(file, protocol).dump(obj)
File "/usr/lib/python2.7/pickle.py", line 224, in dump
self.save(obj)
File "/usr/lib/python2.7/pickle.py", line 331, in save
self.save_reduce(obj=obj, *rv)
File "/usr/lib/python2.7/pickle.py", line 425, in save_reduce
save(state)
File "/usr/lib/python2.7/pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "/usr/lib/python2.7/pickle.py", line 554, in save_tuple
save(element)
File "/usr/lib/python2.7/pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "/usr/lib/python2.7/pickle.py", line 655, in save_dict
self._batch_setitems(obj.iteritems())
File "/usr/lib/python2.7/pickle.py", line 687, in _batch_setitems
save(v)
File "/usr/lib/python2.7/pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "/usr/lib/python2.7/pickle.py", line 606, in save_list
self._batch_appends(iter(obj))
File "/usr/lib/python2.7/pickle.py", line 639, in _batch_appends
save(x)
File "/usr/lib/python2.7/pickle.py", line 286, in save
f(self, obj) # Call unbound method with explicit self
File "/usr/lib/python2.7/pickle.py", line 655, in save_dict
self._batch_setitems(obj.iteritems())
File "/usr/lib/python2.7/pickle.py", line 687, in _batch_setitems
save(v)
File "/usr/lib/python2.7/pickle.py", line 306, in save
rv = reduce(self.proto)
MemoryError