Draft of test.
Renamed the new loading test.
This test version shows the failure.
Add CLEAR-ASDF-CACHE.
Export REINITIALIZE-SOURCE-REGISTRY-AND-RETRY, and CLEAR-ASDF-CACHE.
Tweak definition of and export REINITIALIZE-SOURCE-REGISTRY-AND-RETRY.
Added more verbosity for debugging.
Merge branch 'master' into bug1335323
New test for cache correctness.

It seems that the cache may override the error flag for FIND-SYSTEM.
Fix for bug where caching mistakenly overrides error flag in FIND-SYSTEM.

This required refactoring to move
REINITIALIZE-SOURCE-REGISTRY-AND-RESTART to correct location.

This shoudl also fix bug13353423, but we still need a better test.
Merge branch 'master' into bug1335323
Simpler FIND-SYSTEM patch by just not doing negative caching. Thanks to Fare.
Cleaned up a bunch of debugging cruft.
Test still doesn't work, but that seems to be because the testing code
itself establishes an ASDF cache, making the restart I want inaccessible
from test code.
Another take on bug1335323
Drop caching from LOCATE-SYSTEM.

Caching negative results here causes pervasive problems, and removing
negative caching only would be very messy, so we are removing caching
here altogether.

This required some modification to the test code, which was directly
using LOCATE-SYSTEM, and LOCATE-SYSTEM cannot be safely invoked unless
the ASDF-CACHE has been established.
Remove loop and restart-case from find-system;
the functionality was moved to call-with-asdf-cache before where it belongs.
Replace a trivial if-let by or.
Tweaked the order of requirements for test target.

Verbose output from doc formatting was making test results hard to find
sometimes.
Merge branch 'master' into bug1335323
Bump version to 3.1.2.9