[PATCH 0/2] Travis CI: skip commits with successfully built and tested trees

Travis CI dutifully builds and tests each new branch tip, even if its tree has previously been successfully built and tested. This happens often enough in contributors' workflows, when a work-in-progress branch is rebased changing e.g. only commit messages or the order or number of commits while leaving the resulting code intact, and is then pushed to a Travis CI-enabled GitHub fork.

This is wasting Travis CI's resources and is sometimes scary-annoying when the new tip commit with a tree identical to the previous, successfully tested one is suddenly reported in red, because one of the OSX build jobs happened to exceed the time limit yet again.

These two patches extend our Travis CI build scripts to skip building commits whose trees have previously been successfully built and tested.

These patches should go on top of the "Rest of the Travis CI fixes" patch series, just posted at:

  https://public-inbox.org/git/20171227163603.13313-1-szeder.dev@gmail.com/

SZEDER Gábor (2):
  travis-ci: don't try to create the cache directory unnecessarily
  travis-ci: record and skip successfully built trees

 ci/lib-travisci.sh        | 43 +++++++++++++++++++++++++++++++++++++++++++
 ci/run-linux32-docker.sh  |  2 ++
 ci/run-static-analysis.sh |  2 ++
 ci/run-tests.sh           |  3 ++-
 ci/run-windows-build.sh   |  2 ++
 ci/test-documentation.sh  |  2 ++
 6 files changed, 53 insertions(+), 1 deletion(-)