Fix Perl module Module::Pluggable such that it can find plugins that live in
symlinked directories.

Patch borrowed/adapted from Nixpkgs.

--- Module-Pluggable-5.2/lib/Module/Pluggable/Object.pm   2015-04-08 23:28:48.120164135 -0500
+++ Module-Pluggable-5.2/lib/Module/Pluggable/Object.pm   2015-04-08 23:30:27.032166704 -0500
@@ -164,7 +164,7 @@
         my $sp = catdir($dir, (split /::/, $searchpath));

         # if it doesn't exist or it's not a dir then skip it
-        next unless ( -e $sp && -d _ ); # Use the cached stat the second time
+        next unless ( -e $sp );

         my @files = $self->find_files($sp);

@@ -279,7 +279,7 @@
                              (my $path = $File::Find::name) =~ s#^\\./##;
                              push @files, $path;
                            }
-                      }, $search_path );
+                      }, "$search_path/." );
     }
     #chdir $cwd;
     return @files;</td><td class='sub right'></td></tr></table>
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<tr><td><span title='2021-04-12 14:12:49 +0200'>2021-04-12</span></td><td><a href='/guix/commit/gnu/tests/docker.scm?id=e1a465209925c43871ce581c2752ae620fbedd3a'>tests: docker: Increase VM building memory size to 1024MiB.</a><span class='msg-avail'>...<span class='msg-tooltip'>This fixes the following error when running the "docker-system" test:

In ice-9/ftw.scm:
   553:30  1 (_ #&lt;directory stream db6660&gt;)
In unknown file:
           0 (readdir #&lt;directory stream db6660&gt;)

ERROR: In procedure readdir:
In procedure readdir: Cannot allocate memory

* gnu/tests/docker.scm (%test-docker-system): Bump image building VM memory
size to 1024 MiB.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2021-02-25 11:29:35 +0100'>2021-02-25</span></td><td><a href='/guix/commit/gnu/tests/docker.scm?id=2b0026813bc18258dd6fbecd69723df0267994b7'>tests: docker-system: Increase VM memory.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests/docker.scm (run-docker-system-test)[vm]: Increase
'memory-size'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-11-06 16:16:02 +0100'>2020-11-06</span></td><td><a href='/guix/commit/gnu/tests/docker.scm?id=3c69e81d85e337ccceb2248c497bd1732a63f7ec'>tests: docker-system: Increase VM memory.</a><span class='msg-avail'>...<span class='msg-tooltip'>The test was failing with ENOSPC.

* gnu/tests/docker.scm (run-docker-system-test)[vm]: Increase 'memory-size'.
(%test-docker-system): Change 'locale-libcs' for the OS passed to
'system-docker-image'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-07-17 22:13:58 +0200'>2020-07-17</span></td><td><a href='/guix/commit/gnu/tests/docker.scm?id=c9ea5dfdbe1c4758cfbd7b4b665219d4b8a4bad6'>tests: docker-system: Use guile-3.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>This helps find the (json) module in the virtual machine.

* gnu/tests/docker.scm (build-tarball&amp;run-docker-test,
run-docker-system-test): Replace guile-2.2 with guile-3.0.
</span></span></td><td>Jakub Kądziołka</td></tr>
<tr><td><span title='2020-03-09 23:46:36 +0100'>2020-03-09</span></td><td><a href='/guix/commit/gnu/tests/docker.scm?id=0e42a1643ea5a0cc4ddb81687c608ba407fdcdbb'>tests: docker-system: Increase memory requirement.</a><span class='msg-avail'>...<span class='msg-tooltip'>The system image would no longer fit in memory, starting from commit
8c7eb58453870f380a077c7cfd8dafa97bb8e13f.

* gnu/tests/docker.scm (run-docker-system-test): Set 'memory-size' to 3500.
</span></span></td><td>Ludovic Courtès</td></tr>