What version of Djblets are you using?
Current branch release-2.0.x (4d1770de6e861ac7d81f2fbd78c21e7ef6fa24fd)
Which module(s) have the problem?
python setup.py build_media
What steps will reproduce the problem?

Create virtualenv
Go to current django-evolution
python setup.py develop
Go to current djblets
python setup.py develop


What is the expected output? What do you see instead?
Expect success... see an exception of lessc


What version of Python and Django?
Python 3.8.5, Django 1.11.29
Please provide any additional information below.
Traceback (most recent call last):

  File "contrib/internal/build-media.py", line 37, in <module>

    call_command('collectstatic', interactive=False, verbosity=2)

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/django/core/management/init.py", line 131, in call_command

    return command.execute(args, defaults)

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/django/core/management/base.py", line 330, in execute

    output = self.handle(*args, options)

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py", line 199, in handle

    collected = self.collect()

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py", line 139, in collect

    for original_path, processed_path, processed in processor:

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/storage.py", line 26, in post_process

    packager.pack_stylesheets(package)

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/packager.py", line 98, in pack_stylesheets

    return self.pack(package, self.compressor.compress_css, css_compressed,

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/packager.py", line 113, in pack

    paths = self.compile(

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/packager.py", line 103, in compile

    return self.compiler.compile(

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/compilers/init.py", line 56, in compile

    return list(executor.map(_compile, paths))

  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 611, in result_iterator

    yield fs.pop().result()

  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 439, in result

    return self.__get_result()

  File "/usr/lib/python3.8/concurrent/futures/_base.py", line 388, in __get_result

    raise self._exception

  File "/usr/lib/python3.8/concurrent/futures/thread.py", line 57, in run

    result = self.fn(self.args, self.kwargs)

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/compilers/init.py", line 41, in _compile

    compiler.compile_file(infile, outfile,

  File "/home/andre/git/djblets/djblets/pipeline/compilers/less.py", line 43, in compile_file

    self.execute_command((

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/pipeline/compilers/init.py", line 133, in execute_command

    raise CompilerError(

pipeline.exceptions.CompilerError: <filter object at 0x7f89015cddf0> exit code 1

b'internal/fs/utils.js:701\n    throw new ERR_INVALID_ARG_TYPE(\n    ^\n\nTypeError [ERR_INVALID_ARG_TYPE]: The "data" argument must be of type string or an instance of Buffer, TypedArray, or DataView. Received an instance of SourceMapGenerator\n    at writeFile (fs.js:1385:5)\n    at go$writeFile (/home/andre/git/djblets/node_modules/graceful-fs/graceful-fs.js:139:14)\n    at Object.writeFile (/home/andre/git/djblets/node_modules/graceful-fs/graceful-fs.js:136:12)\n    at writeSourceMap (/home/andre/git/djblets/node_modules/less/bin/lessc:183:10)\n    at writeSourceMapIfNeeded (/home/andre/git/djblets/node_modules/less/bin/lessc:207:7)\n    at /home/andre/git/djblets/node_modules/less/bin/lessc:299:11\n    at /home/andre/git/djblets/node_modules/less/bin/lessc:237:11\n    at /home/andre/git/djblets/node_modules/graceful-fs/graceful-fs.js:144:16\n    at /home/andre/git/djblets/node_modules/graceful-fs/graceful-fs.js:61:14\n    at FSReqCallback.oncomplete (fs.js:164:23) {\n  code: \'ERR_INVALID_ARG_TYPE\'\n}\n'

Traceback (most recent call last):

  File "setup.py", line 455, in <module>

    setup(

  File "/home/andre/tmp/rb/rb4/env/lib/python3.8/site-packages/setuptools/init.py", line 165, in setup

    return distutils.core.setup(attrs)

  File "/usr/lib/python3.8/distutils/core.py", line 148, in setup

    dist.run_commands()

  File "/usr/lib/python3.8/distutils/dist.py", line 966, in run_commands

    self.run_command(cmd)

  File "/usr/lib/python3.8/distutils/dist.py", line 985, in run_command

    cmd_obj.run()

  File "setup.py", line 254, in run

    raise RuntimeError('Failed to build media files')

RuntimeError: Failed to build media files