v1.4

• Always cancel, and wait for, a mpb.Progress pool
• Remove bar != nil checks
• Use separate short-term progress pools for layers, and config
• Move creation of destInfos and destIDs closer to its uses
• Add copier.newProgressPool
• Add a mpb.Progress parameter to createProgressBar
• Remove shortDigest
• Move the responsibility for aligning progress bars into createProgressBar
• Remove copier.progresWG
• Don't call SetTotal(0, true)
• progress bars: use github.com/vbauerster/mpb
• storage: set a returned image's .Digest to the specified digest
• WIP: Support multiple manifests in c/storage
• Don't update manifests when writing to digested references
• Fallback to v2s2 if OCI manifest upload fails on ECR
• Refactor isManifestInvalidError()
• docker-image-src/getExternalBlob: handle nil resp
• Remove an unnecessary pipe in ostreeImageSource.GetBlob
• ostreeImageSource.GetBlob(): close mfz when we're done with it
• sysregistriesv2: Export registries struct for v1 format
• Lock docker/tarfile/src.ensureCachedDataIsPresent
• Mark docker/tarfile's GetBlob thread-safe
• Remove newlines from logging
• dockerImageDestination: hasThreadSafePutBlob -> true
• docker client: make extraScope a parameter
• Move to version 1.5-dev
• Bump to version 1.4
• copy: print singles lines when reportWriter is not a tty
• add @vrothberg to the list of MAINTAINERS
• Revert ".travis: specify HOME env variable"