Odd error message from Git hook

[Gerald Pfeifer]

On Sun, 26 Oct 2025, Jonathan Wakely wrote:
>>> I saw this last month, where there were spaces instead of a tab - so a
>>> diagnosis is correct, just the specific error message is off: That line
>>> definitely should not start with a tab.
>>>
>>> Who can help and address that?
> If that line wasn't the problem, could you tell us what the real error in
> the commit msg was? It's a bit hard to try and reproduce it (and then fix
> the hook) if we only see a correct line with the report of an unspecified
> problem that isn't shown :)

Apologies, in my mind I though I had described the issue - while I clearly 
did not.

In

  remote: *** ERR: line should start with a tab: "Signed-off-by:  Jonathan Grant <jg@jguk.org>"

indeed there were spaces instead of a tab. Just they were between the 
colon and the word "Jonathan". So it's the "line SHOULD START with a tab"
(emphasis mine) that's confusing.

Is there maybe one regexp or condition that triggers the error and covers 
both cases: (a) leading spaces instead of a tab and (b) spaces instead of 
a tab after that pseudo-header?

Gerald