Description: Don't fail documentation build on examples exceptions

If example code outputs an error when run,
ipython (ipython:: blocks) now fails the whole build by default,
and tools/nbgenerate.py (.ipynb files) now leaves out that file
(leaving a broken link in the examples index).

As some examples use downloaded data and are hence expected to be
unrunnable on a Debian buildd, this instead keeps them
(::ipython with error output, .ipynb without output).

Author: Rebecca N. Palmer <rebecca_palmer@zoho.com>
Forwarded: not-needed

--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -66,6 +66,7 @@ else:
 
 # nbsphinx options
 nbsphinx_allow_errors = True
+ipython_warning_is_error = False
 # sphinxcontrib-spelling options
 spelling_word_list_filename = ['spelling_wordlist.txt', 'names_wordlist.txt']
 spelling_ignore_pypi_package_names = True
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -34,6 +34,8 @@ html:
 	mkdir -p $(BUILDDIR)/source/examples/notebooks/generated
 	# Black list notebooks from doc build here
 	$(TOOLSPATH)$(NOTEBOOKBUILD) --parallel --report-errors --skip-existing --execute-only --execution-blacklist statespace_custom_models
+	@echo "Copying notebooks that failed execution (there are usually several in Debian because some need network and/or dependencies we don't have)"
+	cp -nav ../examples/notebooks/*.ipynb -t source/examples/notebooks/generated || true
 	@echo "Running sphinx-build"
 	@echo @$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) $(O)
 	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) $(O)