Flakky tests

When running install scripts from https://github.com/twosigma/beakerx_tests/blob/master/dev_scripts/install_kernels_notebook.sh

To be more precise:
```
(cd ../../beakerx_kernel_scala/scala-dist; pip install -r requirements.txt --verbose; beakerx_kernel_scala install)
```

More than once I had failing tests:

```
51 tests completed, 2 failed
> Task :sparkex:test FAILED
> Task :sparkex:copyDependencies
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':sparkex:test'.
> There were failing tests. See the report at: file:///home/lukasz/code/codete/beakerx_kernel_scala/sparkex/build/reports/tests/test/index.html
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org
Deprecated Gradle features were used in this build, making it incompatible with Gradle 7.0.
Use '--warning-mode all' to show the individual deprecation warnings.
See https://docs.gradle.org/6.4.1/userguide/command_line_interface.html#sec:command_line_warnings
BUILD FAILED in 1m 39s
23 actionable tasks: 10 executed, 13 up-to-date
Traceback (most recent call last):
File "", line 1, in
File "/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setup.py", line 85, in
setup(**setup_args)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/setuptools/__init__.py", line 163, in setup
return distutils.core.setup(**attrs)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/distutils/core.py", line 148, in setup
dist.run_commands()
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/distutils/dist.py", line 966, in run_commands
self.run_command(cmd)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/distutils/dist.py", line 985, in run_command
cmd_obj.run()
File "/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setupbase.py", line 164, in run
[self.run_command(cmd) for cmd in cmds]
File "/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setupbase.py", line 164, in
[self.run_command(cmd) for cmd in cmds]
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/distutils/cmd.py", line 313, in run_command
self.distribution.run_command(command)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/distutils/dist.py", line 985, in run_command
cmd_obj.run()
File "/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setupbase.py", line 135, in run
self.skip_test_option(skip_tests)], cwd=path)
File "/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setupbase.py", line 147, in run
return check_call(cmd, *args, **kwargs)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/subprocess.py", line 363, in check_call
raise CalledProcessError(retcode, cmd)
subprocess.CalledProcessError: Command '['./gradlew', '--no-daemon', 'install', '-Dskip.tests=False']' returned non-zero exit status 1.
Rolling back uninstall of beakerx-kernel-scala
Moving to /home/lukasz/miniconda3/envs/beakerx/bin/beakerx_kernel_scala
from /tmp/pip-uninstall-0tonykz1/beakerx_kernel_scala
Moving to /home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/beakerx-kernel-scala.egg-link
from /tmp/pip-uninstall-im4cu27o/beakerx-kernel-scala.egg-link
Replacing /home/lukasz/miniconda3/envs/beakerx/bin/beakerx_kernel_scala from /tmp/pip-uninstall-0tonykz1/beakerx_kernel_scala
Replacing /home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/beakerx-kernel-scala.egg-link from /tmp/pip-uninstall-im4cu27o/beakerx-kernel-scala.egg-link
Rolling /home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/easy-install.pth back to previous state
ERROR: Command errored out with exit status 1: /home/lukasz/miniconda3/envs/beakerx/bin/python3.7 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setup.py'"'"'; __file__='"'"'/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' develop --no-deps Check the logs for full command output.
Exception information:
Traceback (most recent call last):
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/cli/base_command.py", line 216, in _main
status = self.run(options, args)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/cli/req_command.py", line 182, in wrapper
return func(self, options, args)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/commands/install.py", line 421, in run
pycompile=options.compile,
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/req/__init__.py", line 90, in install_given_reqs
pycompile=pycompile,
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/req/req_install.py", line 799, in install
unpacked_source_directory=self.unpacked_source_directory,
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/operations/install/editable_legacy.py", line 51, in install_editable
cwd=unpacked_source_directory,
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/pip/_internal/utils/subprocess.py", line 242, in call_subprocess
raise InstallationError(exc_msg)
pip._internal.exceptions.InstallationError: Command errored out with exit status 1: /home/lukasz/miniconda3/envs/beakerx/bin/python3.7 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setup.py'"'"'; __file__='"'"'/home/lukasz/code/codete/beakerx_kernel_scala/scala-dist/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' develop --no-deps Check the logs for full command output.
Removed build tracker: '/tmp/pip-req-tracker-jblhyla0'
Traceback (most recent call last):
File "/home/lukasz/miniconda3/envs/beakerx/bin/beakerx_kernel_scala", line 33, in
sys.exit(load_entry_point('beakerx-kernel-scala', 'console_scripts', 'beakerx_kernel_scala')())
File "/home/lukasz/miniconda3/envs/beakerx/bin/beakerx_kernel_scala", line 22, in importlib_load_entry_point
for entry_point in distribution(dist_name).entry_points
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/importlib_metadata/__init__.py", line 558, in distribution
return Distribution.from_name(distribution_name)
File "/home/lukasz/miniconda3/envs/beakerx/lib/python3.7/site-packages/importlib_metadata/__init__.py", line 215, in from_name
raise PackageNotFoundError(name)
importlib_metadata.PackageNotFoundError: No package metadata was found for beakerx-kernel-scala```