fix is_juliaup_installed for invalid path
#931
| Job | Run time |
|---|---|
| 6m 43s | |
| 6m 34s | |
| 2m 18s | |
| 7m 44s | |
| 2m 19s | |
| 3m 55s | |
| 2m 17s | |
| 4m 24s | |
| 2m 44s | |
| 7m 52s | |
| 1m 6s | |
| 11m 1s | |
| 1m 40s | |
| 2m 9s | |
| 2m 6s | |
| 2m 22s | |
| 1m 50s | |
| 1m 41s | |
| 1m 58s | |
| 1m 40s | |
| 1m 51s | |
| 57s | |
| 1h 17m 11s |