Raise the bors timeout to four hours

bors's timeout should always be twice a long as the test suite takes.
This is to allow Travis to fast-fail a test; if one of the builders
immediately reports a failure, then bors will move on to the next batch,
leaving the slower builders to work through the already-doomed run and
the next one.

At the time this was written, nix's test suite took about an hour to run.
The timeout was raised to four hours, instead of two, to give nix room
to grow and time for delays on Travis's end.

Author: notriddle

bors.toml

@@ -1 +1,15 @@
+# Gate on Travis CI
 status = ["continuous-integration/travis-ci/push"]
+
+# Set bors's timeout to 4 hours
+#
+# bors's timeout should always be twice a long as the test suite takes.
+# This is to allow Travis to fast-fail a test; if one of the builders
+# immediately reports a failure, then bors will move on to the next batch,
+# leaving the slower builders to work through the already-doomed run and
+# the next one.
+#
+# At the time this was written, nix's test suite took about an hour to run.
+# The timeout was raised to four hours, instead of two, to give nix room
+# to grow and time for delays on Travis's end.
+timeout_sec = 14400