Failure building docs for uwt 0.3.3

[jonludlam]

Failed during linking.

Logs: https://docs.ci.ocaml.org/job/2021-06-20/112137-voodoo-do-330137

odoc: internal error, uncaught exception:
      Failure("Error")
      Raised at file "pervasives.ml", line 32, characters 17-33
      Called from file "src/xref2/subst.ml", line 806, characters 13-29
      Called from file "src/xref2/subst.ml", line 848, characters 16-30
      Called from file "src/xref2/subst.ml", line 914, characters 17-50
      Called from file "src/xref2/subst.ml", line 591, characters 30-46
      Called from file "src/xref2/subst.ml", line 662, characters 31-55
      Called from file "src/xref2/subst.ml", line 726, characters 11-32
      Called from file "src/xref2/tools.ml", line 143, characters 31-53
      Called from file "list.ml", line 67, characters 20-23
      Called from file "src/xref2/tools.ml", line 107, characters 4-1023
      Called from file "src/xref2/ref_tools.ml", line 660, characters 18-65
      Called from file "src/xref2/link.ml", line 136, characters 12-45
      Called from file "src/xref2/lookup_failures.ml", line 10, characters 10-14
      Called from file "src/xref2/lookup_failures.ml" (inlined), line 38, characters 26-58
      Called from file "src/xref2/link.ml", line 202, characters 14-77
      Called from file "list.ml", line 67, characters 20-23
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "src/xref2/link.ml", line 166, characters 34-54
      Called from file "src/xref2/lookup_failures.ml", line 10, characters 10-14
      Called from file "src/xref2/lookup_failures.ml" (inlined), line 38, characters 26-58
      Called from file "src/xref2/link.ml", line 202, characters 14-77
      Called from file "list.ml", line 67, characters 20-23
      Called from file "src/xref2/link.ml", line 212, characters 21-48
      Called from file "src/xref2/link.ml", line 343, characters 29-47
      Called from file "list.ml", line 67, characters 20-23
      Called from file "list.ml", line 67, characters 32-39
      Called from file "src/xref2/link.ml", line 325, characters 14-44
      Called from file "src/xref2/link.ml", line 579, characters 29-49
      Called from file "src/xref2/link.ml", line 404, characters 34-64
      Called from file "src/xref2/link.ml", line 374, characters 16-45
      Called from file "src/xref2/link.ml", line 336, characters 36-49
      Called from file "list.ml", line 67, characters 20-23
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "list.ml", line 67, characters 32-39
      Called from file "src/xref2/link.ml", line 325, characters 14-44
      Called from file "src/xref2/link.ml", line 441, characters 18-60
      Called from file "src/xref2/link.ml", line 349, characters 29-45
      Called from file "list.ml", line 67, characters 20-23
      Called from file "list.ml", line 67, characters 32-39
      Called from file "src/xref2/link.ml", line 325, characters 14-44
      Called from file "src/xref2/link.ml", line 218, characters 26-69
      Called from file "src/model/error.ml", line 87, characters 18-22
      Called from file "src/model/error.ml", line 65, characters 12-16
      Re-raised at file "src/model/error.ml", line 70, characters 4-11
      Called from file "src/xref2/lookup_failures.ml", line 10, characters 10-14
      Called from file "src/odoc/odoc_link.ml", line 42, characters 6-37
      Called from file "src/odoc/bin/main.ml", line 255, characters 10-70
      Called from file "cmdliner_term.ml", line 25, characters 19-24
      Called from file "cmdliner_term.ml", line 23, characters 12-19
      Called from file "cmdliner.ml", line 117, characters 32-39

[jonludlam]

Fixed by #708