bug#65763: Error opening a file from a Git working directory if Git is not installed

[Dmitry Gutov <dmitry@gutov.dev>]

On 06/09/2023 15:13, Eli Zaretskii wrote:
>> From: Paul Pogonyshev<pogonyshev@gmail.com>
>> Date: Wed, 6 Sep 2023 09:29:59 +0200
>> Cc:65763@debbugs.gnu.org
>>
>> The problem appears to be only with `debug-on-error'. However, there are cases where you cannot
>> control it at all, e.g. with ERT (probably also Buttercup or any other testing framework). In effect, an
>> ERT test fails for a "random" reason, depending on which machine it is executed, i.e. it fails inside
>> that Docker container.
> I see.
> 
> Well, we could then protect the execution of the problematic form "by
> hand" by using condition-case-unless-debug.  Dmitry, WDYT?

Maybe the solution is to use the straight condition-case rather than 
condition-case-unless-debug? Because otherwise as long as 
condition-case-unless-debug is used, we would always have this problem.

Rewriting with-demoted-errors is not an option, of course, but we could 
create a special, shorted version of it for vc.

Another option, though, is to rewrite the ERT tests in question: e.g. to 
bind vc-handled-backends to nil, or to some other value if the presence 
of certain VC programs is known and expected in advance.