do not attach PIPE file handle on STDIN of run_shell_cmd unless there are contents for it
#4025
| Job | Run time |
|---|---|
| 1m 27s | |
| 1m 27s | |
| 2m 5s | |
| 2m 0s | |
| 1m 38s | |
| 1m 47s | |
| 1m 28s | |
| 1m 38s | |
| 13m 30s |