Re: [PATCH 10/10] t: make 'test_i18ngrep' more informative on failure

> When 'test_i18ngrep' can't find the expected pattern, it exits
> completely silently; when its negated form does find the pattern that
> shouldn't be there, it prints the matching line(s) but otherwise exits
> without any error message.  This leaves the developer puzzled about
> what could have gone wrong.
> 
> Make 'test_i18ngrep' more informative on failure by printing an error
> message including the invoked 'grep' command and the contents of the
> file it had to scan through.

> Note that this "dump the scanned file" part is not quite perfect, as
> it dumps only the file specified as the function's last positional
> parameter, thus assuming that there is only a single file parameter.
> I think that's a reasonable assumption to make, one that holds true in
> the current code base.  And even if someone were to scan multiple
> files at once in the future, the worst thing that could happen is that
> the verbose error message won't include the contents of all those
> files, only the last one.  Alas, we can't really do any better than
> this, because checking whether the other positional parameters match a
> filename can result in false positives: 't3400-rebase.sh' and
> 't3404-rebase-interactive.sh' contain one test each, where the
> 'test_i18ngrep's pattern verbatimely matches a file in the trash
> directory.  Note that the absence of a file parameter is not an issue,
> because the lint check added in the previous commit ensures that
> 'test_i18ngrep' never reads from its standard input, consequently
> there must be a file parameter.