Fix broken MD5 hash cache.

[Melraidin]

This change fixes issues causing no matches to occur for existing objects at S3 in some cases. This issue caused all versions of a package in a repo to be uploaded again to S3.

Lookups in the cache of file MD5s were failing as the key in the map had its prefix stripped while the key used for the lookup did not have the prefix stripped. This change stops stripping the prefix when building the cache.

Retrieving object MD5s from object metadata (as opposed to the etag that comes with the object list) were failing as the key in the metadata map is now "md5" (all lowercase) vs. "Md5" that was used pre-v2 AWS SDK.

Checklist

• unit-test added (if change is algorithm)
• functional test added/updated (if change is functional)
• man page updated (if applicable)
• bash completion updated (if applicable)
• documentation updated
• author name in AUTHORS

[neolynx]

I wonder why the prefix was added on one side only, and what it's purpose is. If the prefix somehow makes sense, maybe we should add it in the missing part ?

The tests are now complaining about the missing prefix, so they should be fixed (no more prefix) if we decide to drop the prefix...

[neolynx]

the following system tests fail:

• t06_publish: S3Publish2Test t06_publish.s3: publish to S3: publish update removed some packages
• t06_publish: S3Publish3Test t06_publish.s3: publish to S3: publish switch - removed some packages
• t06_publish: S3Publish5Test t06_publish.s3: publish to S3: publish drop - component cleanup
• t06_publish: S3Publish6Test t06_publish.s3: publish to S3: publish update removed some packages with SSE AES256

in order to test, create a aws.creds file in the git root (don't add it to git):

export AWS_ACCESS_KEY_ID=123452
export AWS_SECRET_ACCESS_KEY=asdfghrew

and run: make docker-system-tests
(after creating the dev docker with make docker-build-aptly-dev)

[neolynx]

the following unit tests fail:

• FAIL: public_test.go:130: PublishedStorageSuite.TestFilelist
• FAIL: public_test.go:153: PublishedStorageSuite.TestFilelistPlusWorkaround
• FAIL: public_test.go:218: PublishedStorageSuite.TestRemoveDirs
• FAIL: public_test.go:234: PublishedStorageSuite.TestRemoveDirsPlusWorkaround

run unit tests locally with: make docker-unit-tests