verify sign error: VerifyError: No rules for this file in ContentManager.py line 988 > 814

### Step 1: Please describe your environment

* ZeroNet version: rev4555
* Operating system: Linux
* Web browser: FF

### Step 2: Describe the problem:

I have been running Zeronet for 30 minutes and in the debug.log i have found 40 000 times the error:
`verify sign error: VerifyError: No rules for this file in ContentManager.py line 988 > 814`
and it is now growing a few hundred per minute (Log mode - EVERYTHING).

full log line example:
`WARNING Site:1MoonP..5ux2 data/users/1FjdDwGPpDHUn3Pp19ey486HuePfvuiyNg/content.json: verify sign error: VerifyError: No rules for this file in ContentManager.py line 988 > 814`

but it happen also for other sites, like ThunderWave

Maybe related to my attempt to [rebuild content.db](https://github.com/HelloZeroNet/ZeroNet/issues/2741) ?

What do you suggest please?