I have the same problem. Recompiling and reinstalling the packages fixed the issue.
I recompiled libhttp-ocaml-dev (which I believe was not useful at all), libocamlnet-ocaml-dev and libnetclient-ocaml-dev. I believe the last package finally resolved the issue.
I also installed libdbi-ocaml-dev, which depends on pcre, and managed to load its postgresql module without problems (which depends on pcre) so I believe this is the right way to fix.
I have the same problem. Recompiling and reinstalling the packages fixed the issue.
I recompiled libhttp-ocaml-dev (which I believe was not useful at all), libocamlnet- ocaml-dev and libnetclient- ocaml-dev. I believe the last package finally resolved the issue.
I also installed libdbi-ocaml-dev, which depends on pcre, and managed to load its postgresql module without problems (which depends on pcre) so I believe this is the right way to fix.