obshistory: only display each revision once in debugobshistory
When using a revision range, the same precursor could have been
displayed more than once. Use a cache to display each revision
only once.
It's a fix until we found the nicest way to display obs history.
all: tutorials/tutorial.rst static/logo-evolve.ico
sphinx-build . ../html/
tutorials/tutorial.rst: tutorials/tutorial.t
python test2rst.py tutorials/
static/logo-evolve.ico: static/logo-evolve.svg
convert -resize 36x36 static/logo-evolve.svg static/logo-evolve.ico