With c18n, git crashes with a tag violation when Ctrl-C is used

[rwatson]

This is with the c18n-ubiq branch, and c18n enabled by default.

When I use git log on a large repo (e.g., CheriBSD), and hit Ctrl-C, I frequently get a crash:

commit 0209c8e659cd4abe4b99359312135137a228a164
Author: Mark Johnston <markjdb@gmail.com>
Date:   Fri Mar 8 23:26:27 2024 -0500

    caprevoke: Add a sysctl to set the default sync/async revocation policy

    Akin to other revocation policy sysctls, this one sets a flag which is
^C
In-address space security exception (core dumped)

This doesn’t appear to happen with c18n disabled. No debugging symbols, and limited GDB support for c18n, so not much to go on currently:

# gdb `which git` git.core 
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Reading symbols from /usr/local/bin/git...
(No debugging symbols found in /usr/local/bin/git)
[New LWP 100220]
Core was generated by `git log'.
Program terminated with signal SIGPROT, CHERI protection violation.
Capability tag fault.
#0  0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in ?? ()
#1  0x0000000040651f04 in ?? ()
Backtrace stopped: previous frame identical to this frame (corrupt stack?)

[dpgao]

Fixed in #2066.