SEGV in cgit-1.2.3 on following logs of a nonexistent file with cache

[Marko Zajc]

Dear cgit developers,

I would like to report a segmentation fault in cgit that can be 
reproduced with the following steps:

1. Set `enable-follow-links` to `1`
2. Set `cache-size` to a non-zero value. I'm not sure if this only
    occurs on specific values, but I've tried a few numbers in the 1 –
    10000 range and they all cause this to happen
3. Have cgit installed and active at least one repository
4. Try following the log of a file that doesn't exist, for example
    `https://git.zx2c4.com/cgit/log/file-that-doesnt-exist?follow=1`

On certain repositories, I am able to consistently reproduce this with 
the above steps, but others seem unaffected. Changing the `cache-size` 
value between 1 and N does not seem to change which repositories are 
affected, but I didn't try that on a very large sample size. For example:

  * git://zajc.eu.org/xheadset.git *is not affected* by this, but
  * git://zajc.eu.org/gogarchiver.git *is affected*

I don't have the stack trace, but I can try getting one in case you're 
unable to reproduce this issue.

I am using Debian 12's build of cgit 1.2.3. I have disabled 
`enable-follow-links` on my own website, so it won't exhibit this behaviour.

- Marko Zajc

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