Allow a cache directory to be passed to the docs Makefile

doc/Makefile

@@ -5,12 +5,13 @@
 PYTHON        ?= python
 SPHINXOPTS    ?=
 SPHINXBUILD   ?= python $(shell which sphinx-build)
+SPHINXCACHE   ?= build/doctrees
 PAPER         ?=
 
 # Internal variables.
 PAPEROPT_a4     = -D latex_paper_size=a4
 PAPEROPT_letter = -D latex_paper_size=letter
-ALLSPHINXOPTS   = -d build/doctrees $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) source
+ALLSPHINXOPTS   = -d $(SPHINXCACHE) $(PAPEROPT_$(PAPER)) $(SPHINXOPTS) source
 DEST = build
 .PHONY: all help clean html dirhtml pickle json htmlhelp qthelp latex changes linkcheck doctest gitwash gh-pages release_notes random_gallery
 

tools/travis_script.sh

@@ -51,10 +51,8 @@ section_end "Install.optional.dependencies"
 
 section "Build.docs"
 if [[ ($PY != 2.6) && ($PY != 3.2) ]]; then
-    SPHINXBUILD="python $(which sphinx-build)"
-    pushd doc
-    $SPHINXBUILD -d $HOME/.cache/sphinx -W source build/html
-    popd
+    export SPHINXCACHE=$HOME/.cache/sphinx
+    make html
 fi
 section_end "Build.docs"