Cannot obtain needed tree

[robocoder]

Failed to update http://satis/repositories/symfony/validator.git, package information from this repository may be outdated (error: Could not read 6929b2c60e909716ddfe74e3eaa1eb5cb9674f0a                                                                                                                  error: Could not read 494a2b92ae36dfafb7375b80996ea8429f177438                                                                                        error: Unable to find 546b2433a42d976039d14a9017dd74b632ee6b97 under http://satis/repositories/symfony/validator.git                                  Cannot obtain needed tree 546b2433a42d976039d14a9017dd74b632ee6b97                                                                                    while processing commit 4a4396297b90c60ad4b48

Failed to update http://satis/repositories/ocramius/proxy-manager.git, package information from this repository may be outdated (error: Unable to find 8f097a32c6f5da55c3fef8288ebbb593dcb1d351 under http://satis/repositories/ocramius/proxy-manager.git                                                  Cannot obtain needed tree 8f097a32c6f5da55c3fef8288ebbb593dcb1d351
while processing commit ef2cc62f85b4ec67501c76e6537dba4506d3a26c.
error: Fetch failed.
error: Could not fetch origin
)

[robocoder]

These are fixed by running:

cd path-to-repo.git
git prune
git gc

Running "git gc" manually isn't generally recommended, so I won't be adding this to medusa.