[prek, comrak] Doesn't work if multiple markdown files are in the same commit

[dwt]

Preface: I suspect this to be a prek issue first, but likely something that also requires a fix in git-hooks.nix.

The problem is that using prek, the comrak in place formatter is called with multiple files in each invocation. This doesn't work as comrak wants to be invoked with only one file per invocation.

This could be worked around with a local wrapper script that then splits up the command line and calls comrak with only one file, but it would probably better for prek to support an additional setting to do this directly and control concurrency in prek instead.

To this end I have already filed bug upstream j178/prek#1471 to fix this, but am also filing a bug here, as this is how I trigger this problem, because there is the option to provide a workaround here, and because it is likely that in the event that upstream fixes this, a change here is also required to trigger that fix.

[benjamb]

It's also possible comrak could be extended to accept multiple files to -i: kivikakk/comrak#377 (comment)

[ilkecan]

The next comrak release should support this: kivikakk/comrak#792