https://gitlab.gnome.org/GNOME/gnome-shell/issues/1854

Index: subprojects/extensions-tool/man/meson.build
--- subprojects/extensions-tool/man/meson.build.orig
+++ subprojects/extensions-tool/man/meson.build
@@ -1,7 +1,7 @@
 custom_target('gnome-extensions.1',
-  input: ['gnome-extensions.txt', 'stylesheet.xsl'],
+  input: 'gnome-extensions.txt',
   output: 'gnome-extensions.1',
-  command: [a2x, '-D', '@OUTDIR@', '--xsl-file', '@INPUT1@', '-f', 'manpage', '@INPUT0@'],
+  command: [a2x, '-D', '@OUTDIR@', '-f', 'manpage', '@INPUT0@'],
   install_dir: mandir + '/man1',
   install: true
 )