Did you mean something like this?:

use strict;
use warnings;

my $file = 'reqtest.pl';
my $fh;

open $fh, ">$file" or die "Can't create file '$file': $!: $^E\n";
print $fh <<'EOT';
BEGIN {
    print STDERR "Hit CTRL+C now!\n";
    sleep 3;
}
1;
EOT
close $fh;

unshift @INC, sub {
    my($coderef, $filename) = @_;
    return unless $filename eq $file;
    open $fh, $filename or die "Can't read file '$file': $!: $^E\n";
    return $fh;
};

$SIG{INT} = sub {
    print "Caught SIGINT. Terminating.\n";
    if (open my $fh2, '<&=' . $*{delete $INC{$file}}) {
        close $fh2 or warn "Can't close fh2: $!: $^E\n";
    }
    else {
        warn "Can't fdopen fh: $!: $^E\n";
    }
    if (-f $file) {
        unlink $file or warn "Can't delete file '$file': $!: $^E\n";
    }
    else {
        print STDERR "file is already deleted (!)\n";
    }
    exit;
};

require $file or die "require() failed\n";

unlink $file or die "Can't delete file '$file': $!: $^E\n";
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It doesn't work :( It prints "Can't fdopen fh: Invalid argument", and if I use Data::Dumper to dump the value corresponding to $file that was delete()'d from %INC then we can see why: it shows:

$VAR1 = sub { "DUMMY" };
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i.e. not a GLOB reference at all.

- Steve