Only clean up old remote directories

Rather than unconditionally deleting the three oldest directories
(which can include directories still in use if there are several
builds running simultaneously).

CHANGES.rst

@@ -115,6 +115,7 @@ Release History
   (it will look for any scripts in the same folder as the static script). (`#166`_)
 - Black will now ignore excluded files even if that filename is passed directly
   to black (e.g. when running through a precommit hook or IDE plugin). (`#161`_)
+- Only delete remote build directories more than a day old. (`#172`_)
 
 .. _#32: https://github.com/nengo/nengo-bones/pull/32
 .. _#101: https://github.com/nengo/nengo-bones/pull/101

nengo_bones/templates/remote.sh.template

@@ -108,7 +108,7 @@ EOF
           flock -x -w 540 200 || exit 1
           echo "$ Obtained cleanup lock"
           {% block remote_cleanup %}
-          ls -tp | grep '{{ pkg }}-' | tail -n +3 | xargs -I {} rm -r -- {}
+          find . -mtime +1 -type d | grep '{{ pkg }}-' | xargs -I {} rm -r -- {}
           {% endblock %}
         ) 200>cleanup.lock
         exit \$?