SameFileError when running snakemake --gernerate-unit-tests

[lenaschneehas]

Dear all,

Snakemake version
I'm using the snakemake version 6.6.0

Describe the bug
I encounter the following error when I try to run a unit test on the our pipeline:

Tries to copy the file from the original location to the same locations instead of into units folder.

Logs
Building DAG of jobs...
Generating unit tests for each rule...
Generating unit test for rule all: .tests/unit/test_all.py.
Generating unit test for rule report_qc: .tests/unit/test_report_qc.py.
Traceback (most recent call last):
File "/home/user/anaconda3/envs/testenv/lib/python3.8/site-packages/snakemake/__init__.py", line 699, in snakemake
success = workflow.execute(
File "/home/user/anaconda3/envs/testenv/lib/python3.8/site-packages/snakemake/workflow.py", line 857, in execute
unit_tests.generate(
File "/home/user/anaconda3/envs/testenv/lib/python3.8/site-packages/snakemake/unit_tests/__init__.py", line 89, in generate
copy_files(job.input, "data")
File "/home/user/anaconda3/envs/testenv/lib/python3.8/site-packages/snakemake/unit_tests/__init__.py", line 83, in copy_files
shutil.copy(f, target)
File "/home/user/anaconda3/envs/testenv/lib/python3.8/shutil.py", line 418, in copy
copyfile(src, dst, follow_symlinks=follow_symlinks)
File "/home/user/anaconda3/envs/testenv/lib/python3.8/shutil.py", line 244, in copyfile
raise SameFileError("{!r} and {!r} are the same file".format(src, dst))
shutil.SameFileError: PosixPath('/home/common/data/output/projects/intermediate_output/merge_clusterings.rds') and '/home/data/output/projects/intermediate_output/merge_clusterings.rds' are the same file

Minimal example
snakemake --profile /PATH_TO_CONFIG/config/profile --conda-frontend conda --generate-unit-tests
Additional context

• I changed the common.py file according to this:
  https://github.com/nikostr/dna-seq-deepvariant-glnexus-variant-calling/blob/e6a945b7a0a3ac006c68a5291e28f7bc8fbafdad/.tests/unit/common.py#L29-L36
  (Except that I'm using .html files as input for the snakemake rules)
• .test/units and all other directories in .test are empty. All content is deleted
• If snakemake --generate-unit-tests is run on a smaller test pipe line it works.

Any help is appreciated!

Lena