### Please describe the problem.

Fresh build of 8.20201129+git100-g2d84bf992-1~ndall+1 when having HOME (base system is Ubuntu) on a crippled FS leads to

```
2021-01-13T03:46:45.0619292Z     prop_relPathDirToFileAbs_basics:                      FAIL (0.01s)
2021-01-13T03:46:45.0620328Z       *** Failed! Falsifiable (after 702 tests):
2021-01-13T03:46:45.0621015Z       TestableFilePath {fromTestableFilePath = "A"}
2021-01-13T03:46:45.0621819Z       TestableFilePath {fromTestableFilePath = "A/"}
2021-01-13T03:46:45.0623170Z       Use --quickcheck-replay=895840 to reproduce.
```

[https://github.com/datalad/git-annex/runs/1692622842?check_suite_focus=true](https://github.com/datalad/git-annex/runs/1692622842?check_suite_focus=true)

[[!meta author=yoh]]
[[!tag projects/datalad]]

> [[fixed|done]] --[[Joey]]
