bug#63150: quilt tests fail

[Jack Hill]

Hi Guix,

The check phase or quilt (below) currently fails (guix commit 
aecc6e70587f8412cbbb9b2c13141de4f534518e). Maybe something with newer grep 
from core-updates? I'm not sure yet (which is why there is no patch 😁).

```
starting phase `check'
[add-filename-check.test]
6 commands (6 passed, 0 failed)
[altered-series.test]
12 commands (12 passed, 0 failed)
[annotate.test]
31 commands (31 passed, 0 failed)
[applied.test]
15 commands (15 passed, 0 failed)
[auto-refresh.test]
14 commands (14 passed, 0 failed)
[backup-files.test]
119 commands (119 passed, 0 failed)
[colon-in-patch-name.test]
23 commands (23 passed, 0 failed)
[comments.test]
11 commands (11 passed, 0 failed)
[conflicts.test]
39 commands (39 passed, 0 failed)
[create-delete.test]
[4] $ mkdir patches -- ok
[6] $ echo delete > delete -- ok
[7] $ quilt new test.diff -- ok
[10] $ quilt add create -- ok
[13] $ echo create > create -- ok
[14] $ quilt refresh -- ok
[17] $ quilt add delete -- ok
[20] $ rm -f delete -- ok
[21] $ quilt refresh -- ok
[23] $ quilt header -r -- ok
[31] $ quilt patches -v create -- ok
[33] $ quilt patches delete -- ok
[36] $ quilt pop -q -- ok
[40] $ quilt patches create -- ok
[42] $ quilt patches -v delete -- ok
[44] $ quilt patches -- /dev/null dev/null null --- -- failed
grep: warning: stray \ before /       != ~
grep: warning: stray \ before /       != ~
grep: warning: stray \ before /       != ~
[46] $ echo create > create -- ok
[47] $ rm -f delete -- ok
[48] $ patch -p1 --dry-run < patches/test.diff -- ok
19 commands (18 passed, 1 failed)
make: *** [Makefile:411: test/.create-delete.ok] Error 1
```

Best,
Jack