Flaky test: fuzzy-cache-main-branch-tracking

[zyla]

Sometimes fails with:

  fuzzy-cache-main-branch-tracking:   FAIL (0.51s)
    Test output was different from 'test/t/fuzzy-cache-main-branch-tracking.out'. Output of ["diff","-u","test/t/fuzzy-cache-main-branch-tracking.out","/tmp/fuzzy-cache-main-branch-tracking2333-9.actual"]:
    --- test/t/fuzzy-cache-main-branch-tracking.out	2024-09-16 09:42:33.702540112 +0000
    +++ /tmp/fuzzy-cache-main-branch-tracking2333-9.actual	2024-09-16 09:43:10.038319218 +0000
    @@ -21,8 +21,4 @@
     [mytask] info | success
     Output in a is: xuq
     *** merging and 'fud' in b, should get fuzzy cache
    -[mytask] info | Inputs changed, running task
    -[mytask] info | Restored fuzzy cache from branch main, hash=22633d092c45c4ee1e6ca68e21dc09bdc038c0c8
    -[mytask] stdout | Expensive computation, previous output is xuq
    -[mytask] info | success
    -Output in b is: duf
    +Output in b is: zab
    
    Use -p '/fuzzy-cache-main-branch-tracking/' to rerun this test only.

Seen both in Actions and locally