Behind the hills next to the Pygmy village of Mabolo, Cameroon in the Central African rain forest, a pipeline is to be built in a few years to carry oil to the Atlantic coast, where it will be shipped to the West. The pipeline, which the World Bank endorsed in June after heated debates, will be a huge project, costing $3.7 billion. It represents a big, risky test for the bank and for African development policies.