Optimize the dependencies list

On a large wiki you can spend a lot of time reading through large lists
of dependencies to see whether files need to be rebuilt (album, with its
one-page-per-photo arrangement, suffers particularly badly from this).

The dependency list is currently a single pagespec, but it's not used like
a normal pagespec - in practice, it's a list of pagespecs joined with the
"or" operator.

Accordingly, change it to be stored as a list of pagespecs. On a wiki
with many tagged photo albums, this reduces the time to refresh after
`touch tags/*.mdwn` from about 31 to 25 seconds.

Getting the benefit of this change on an existing wiki requires a rebuild.

1 files changed, 1 insertions, 1 deletions

diff --git a/ikiwiki-transition b/ikiwiki-transition
index 398b1a3c8..60cea3d54 100755
--- a/ikiwiki-transition
+++ b/ikiwiki-transition
@@ -299,7 +299,7 @@ sub oldloadindex {
 			$pagemtime{$page}=$items{mtime}[0];
 			$oldlinks{$page}=[@{$items{link}}];
 			$links{$page}=[@{$items{link}}];
-			$depends{$page}=$items{depends}[0] if exists $items{depends};
+			$depends{$page}=[$items{depends}[0]] if exists $items{depends};
 			$destsources{$_}=$page foreach @{$items{dest}};
 			$renderedfiles{$page}=[@{$items{dest}}];
 			$pagecase{lc $page}=$page;