+> I would like this feature too, for the very same reasons.
+>
+> To preserve backward compatibility, I tried to implement it in the following way: if `libdir` is a string, it is (as it is right now), a directory in which plugins can be searched; if `libdir` is an array of strings, it is a list of libdirs. The ideal place to put it in would be in subroutine [checkconfig](http://source.ikiwiki.branchable.com/?p=source.git;a=blob;f=IkiWiki.pm;hb=56f8223f9594ae687099dada0c138d669a6f931f#l569). However, plugins are loaded (and option `libdir` is used) in subroutine [loadplugins](http://source.ikiwiki.branchable.com/?p=source.git;a=blob;f=IkiWiki.pm;hb=56f8223f9594ae687099dada0c138d669a6f931f#l713), which is called [just before `checkconfig`](http://source.ikiwiki.branchable.com/?p=source.git;a=blob;f=ikiwiki.in;hb=729991564ec7e1116fc023c51e73b47af8b6fce7#l143).
+>
+> A solution would be to check `libdir` (and turn it into a list if necessary) somewhere in subroutine [getconfig](http://source.ikiwiki.branchable.com/?p=source.git;a=blob;f=ikiwiki.in;hb=729991564ec7e1116fc023c51e73b47af8b6fce7#l26), but I do not know where to put it not to make it look like a bad hack…
+>
+> Any idea about the best place to preprocess `libdir`? Or any better idea to implement this?
+>
+> [[Louis|spalax]]
+
+>> Modifying `getconfig` is not a valid solution, because IkiWiki.pm is also imported by
+>> [[ikiwiki-transition]], [[ikiwiki-calendar]], the regression tests, etc.
+>>
+>> The way I would personally do it is to have a new non-exported function `getlibdirs`
+>> or something, have it do something like this:
+>>
+>> if (! ref $config{libdir}) {
+>> if (length $config{libdir}) {
+>> $config{libdir} = [$config{libdir}];
+>> } else {
+>> $config{libdir} = [];
+>> }
+>> }
+>> return @{$config{libdir}};
+>>
+>> and replace all uses of $config{libdir} with it.
+>>
+>> --[[smcv]]
+>>>
+>>> I implemented it (see branch ``paternal/libdirs``). I used [[smcv]]'s idea, but
+>>> avoiding side effects. I edited documentation as well. As usual, as neither
+>>> English nor Perl are my first languages (damn! I would be so much more
+>>> efficient in Python) feel free to improve my [[!taglink patch]].
+>>> [[!template id=gitbranch branch=spalax/paternal/libdirs browse="https://github.com/paternal/ikiwiki/tree/paternal/libdirs" author="[[Louis|spalax]]"]]
+
+>>>> While reviewing and applying your patch I decided the new
+>>>> "sometimes a list, sometimes not" behaviour of `libdir` was
+>>>> too confusing in documentation, so I made it work like underlaydir(s)
+>>>> instead: ikiwiki will now search each item of `$config{libdirs}`, then
+>>>> `$config{libdir}`. [[done]] --[[smcv]]
+
+>>>>> Good. I cannot see any justification apart from historical reasons, but I
+>>>>> agree with your choice.
+>>>>> -- [[Louis|spalax]]
+