I am making an activity plugin. I uninstalled then reinstalled it. Installation succeeded but this following was displayed. The plugin (as far as I know) isnt explicitly touching the caching system at all.

Upgrading to new version
mod_linkbazaar

( ! ) Warning: rmdir(/home/andrew/Desktop/tempdata/moodledata/dev/master/cache/cachestore_file/default_application/core_string/en_): Directory not empty in /home/andrew/Desktop/code/moodle/dev/master/lib/moodlelib.php on line 10528
Call Stack

1. Time Memory Function Location
   1 0.0023 366192
   Unknown macro: {main}

   ( ) ../index.php:0
   2 0.3546 19801880 upgrade_noncore( ) ../index.php:393
   3 0.4081 19814864 upgrade_plugins( ) ../upgradelib.php:1588
   4 0.4081 19814864 upgrade_plugins_modules( ) ../upgradelib.php:383
   5 15.4108 43074040 purge_all_caches( ) ../upgradelib.php:656
   6 15.8882 43418992 remove_dir( ) ../moodlelib.php:1555
   7 15.8885 43419608 remove_dir( ) ../moodlelib.php:10517
   8 15.8886 43420392 remove_dir( ) ../moodlelib.php:10517
   9 15.8887 43421216 remove_dir( ) ../moodlelib.php:10517
   10 15.8887 43422024 remove_dir( ) ../moodlelib.php:10517
   11 15.9295 43422136 rmdir ( ) ../moodlelib.php:10528

   ( ! ) Warning: rmdir(/home/andrew/Desktop/tempdata/moodledata/dev/master/cache/cachestore_file/default_application/core_string): Directory not empty in /home/andrew/Desktop/code/moodle/dev/master/lib/moodlelib.php on line 10528
   Call Stack

   1. Time Memory Function Location
      1 0.0023 366192

   ( ) ../index.php:0
   2 0.3546 19801880 upgrade_noncore( ) ../index.php:393
   3 0.4081 19814864 upgrade_plugins( ) ../upgradelib.php:1588
   4 0.4081 19814864 upgrade_plugins_modules( ) ../upgradelib.php:383
   5 15.4108 43074040 purge_all_caches( ) ../upgradelib.php:656
   6 15.8882 43418992 remove_dir( ) ../moodlelib.php:1555
   7 15.8885 43419608 remove_dir( ) ../moodlelib.php:10517
   8 15.8886 43420392 remove_dir( ) ../moodlelib.php:10517
   9 15.8887 43421216 remove_dir( ) ../moodlelib.php:10517
   10 15.9470 43421376 rmdir ( ) ../moodlelib.php:10528

( ! ) Warning: rmdir(/home/andrew/Desktop/tempdata/moodledata/dev/master/cache/cachestore_file/default_application): Directory not empty in /home/andrew/Desktop/code/moodle/dev/master/lib/moodlelib.php on line 10528
Call Stack

1. Time Memory Function Location
   1 0.0023 366192
   Unknown macro: {main}

   ( ) ../index.php:0
   2 0.3546 19801880 upgrade_noncore( ) ../index.php:393
   3 0.4081 19814864 upgrade_plugins( ) ../upgradelib.php:1588
   4 0.4081 19814864 upgrade_plugins_modules( ) ../upgradelib.php:383
   5 15.4108 43074040 purge_all_caches( ) ../upgradelib.php:656
   6 15.8882 43418992 remove_dir( ) ../moodlelib.php:1555
   7 15.8885 43419608 remove_dir( ) ../moodlelib.php:10517
   8 15.8886 43420392 remove_dir( ) ../moodlelib.php:10517
   9 15.9763 43420568 rmdir ( ) ../moodlelib.php:10528

   ( ! ) Warning: rmdir(/home/andrew/Desktop/tempdata/moodledata/dev/master/cache/cachestore_file): Directory not empty in /home/andrew/Desktop/code/moodle/dev/master/lib/moodlelib.php on line 10528
   Call Stack

   1. Time Memory Function Location
      1 0.0023 366192

   ( ) ../index.php:0
   2 0.3546 19801880 upgrade_noncore( ) ../index.php:393
   3 0.4081 19814864 upgrade_plugins( ) ../upgradelib.php:1588
   4 0.4081 19814864 upgrade_plugins_modules( ) ../upgradelib.php:383
   5 15.4108 43074040 purge_all_caches( ) ../upgradelib.php:656
   6 15.8882 43418992 remove_dir( ) ../moodlelib.php:1555
   7 15.8885 43419608 remove_dir( ) ../moodlelib.php:10517
   8 15.9774 43419800 rmdir ( ) ../moodlelib.php:10528
   Success