EPUB: fix a volume breaking test

Note that this fixes the test but does not make EPUB behave exactly
like DTBook. It is difficult to achieve exactly the same behavior
because the document structure of EPUB is different from DTBook. As I
explained in #119 (comment)
the document structure is important for volume breaking.

modules/nlb/book-to-pef/src/main/resources/css/nlb-default.scss

@@ -218,7 +218,7 @@ html:not(:has(body ~ body)) > body > section {
 }
 body[epub|type~='part'] ~ body[epub|type~='part'] > section,
 body > section[epub|type~='part'] ~ section[epub|type~='part'] > section { volume-break-inside: -obfl-keep(8); }
-body > section ~ section                                                 { volume-break-inside: -obfl-keep(7); }
+body > section:not(.pef-titlepage, .pef-about) ~ section                 { volume-break-inside: -obfl-keep(7); }
 body > section > section ~ section                                       { volume-break-inside: -obfl-keep(6); }
 body > section > section > section ~ section                             { volume-break-inside: -obfl-keep(5); }
 body > section > section > section > section ~ section                   { volume-break-inside: -obfl-keep(4); }

modules/nlb/book-to-pef/src/test/xprocspec/test_html-to-pef_volume-breaking.xprocspec

@@ -912,7 +912,7 @@
             <x:expect label="The fifth volume should have at least 1 occurence of 'content'" type="xpath" test="contains((//pef:volume)[5]/string-join(.//text(),' '),'⠉⠕⠝⠞⠑⠝⠞')" equals="true()"/>
         </x:scenario>
 
-        <x:scenario label="Content at start of part (or chapter) should be in same volume as first descendant chapter (or subchapter) - short level1, long level2" pending="https://github.com/nlbdev/pipeline/issues/174">
+        <x:scenario label="Content at start of part (or chapter) should be in same volume as first descendant chapter (or subchapter) - short level1, long level2">
             <x:call>
                 <x:input port="source">
                     <x:document type="inline" xml:base="file:/tmp/book.xml">