composer update fails

[ubuntupunk]

composer update
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Updating dependencies (including require-dev)
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Problem 1
- The requested package satooshi/php-coveralls dev-master exists as satooshi/php-coveralls[0.1.0, 0.2.0, 0.3.0, 0.3.1, 0.3.2, 0.4.0, 0.5.0, 2.1.x-dev, dev-gh-pages-bak, v0.6.0, v0.6.1, v0.7.0, v0.7.1, v1.0.0, v1.0.1, v1.0.2, v1.1.0, v2.0.0, v2.1.0] but these are rejected by your constraint.