Breaking improvements:

• major change in dependency handling -- source and package dependencies are now considered equal, so transitive source deps stop overtaking top-level package dependencies.
  May break things for users who relied on that behaviour in mixed repositories
• introduce code coverage options as cover_opts config tuple
• do not install profile-based dependencies of dependencies (stop getting your deps' meck or debug behaviour)
• lock files are sorted to minimize variations in the future and ease diffing

New:

• added proxy support to rebar3 fetches
• SSL certificate validation
• fish shell completions
• add tree command to print the origin of transitive dependencies
• aliased packages such as {uuid, {pkg, uuid_erl}} and {uuid, "1.0.0", {pkg, uuid_erl}} are now supported, where uuid_erl is the package name and uuid the library's
  actual name.
• add support for --file argument in eunit

Fixed:

• fixes to reading app.src.script (for yaws)
• minor template updates
• fixes to profiles application
• reduced memory usage (shell agent, leaks patched)
• fixes for windows (robocopy, symlinks)
• mibs fixes
• fixes to git resource handling (http, custom ssh users supported)
• hooks optimizations
• clear out all usages of 'cd'
• upgrade of dependencies has many improvements
• better error reporting and logging
• major fixes to upgrade and locking mechanisms
• fixes in recompilation of CT suites
• fixes to plugin handling
• directories looking for apps are restricted to what is documented
• escaping paths in shell commands
• edoc provider runs in a 'docs' profile
• clean provider detection of dependencies is fixed
• rebar3 pkgs output is sorted
• fix dialyzer warnings
• fixes to dependency overrides

Changes since alpha-6:

• windows support
• artifacts configuration option for validation of non-Erlang rebar3 generated artifacts (hooks, etc.)
• improvement to escriptize provider
• Dialyzer provider is made compatible with rebar 2.x's so the option set is shared across releases
• exporting config vars to the environment for hooks to be compatible with rebar3's structure
• nicer error messages
• CT fixes
• added a plugins namespace with providers to list and upgrade them
• lots of plugins fixes
• rebar3 builds from packages
• package list is sorted
• fixes to relx argument orders

• ErlyDTL templating replaced by Mustache properly (some bugfixes)
• Size of rebar3 script cut roughly in half
• rebar3 shell has received an overhaul and now has an agent running (r3:do(compile))
• package handling overhaul (including checksum verifications and local disk cache)
• much better plugin handling
• bugs fixed in handling upgrading and lock files
• bug fixes related to path-handling
• fixes to hooks and tests
• addition of options to exclude apps, add various source directories
• tar and release commands are now hookable
• better error reporting
• more bug fixes

Changes since alpha-4:

• rebar3 now bootstraps itself
• app compile fixes on app info contents and config inheritance
• dropping ErlyDTL and going to Mustache for smaller executable sizes
  and faster load time on small CPUs
• dropping erlydtl compile command, ErlyDTL task moved to a plugin
• default dependencies are always fetched in the right place and don't
  need to be copied across profile runs
• escriptize fixes
• unlock command added
• resolving/avoiding clashes when a rebar3 dep and an application
  dependency conflict together
• profile deduplication (rebar3 as test,test,prod,test eunit returns
  the profile/directories for prod+test)
• upgrade command bugfixes to recognize promotion of transient deps to
  top-level deps
• support template when rebar3 is run as an embedded library
• some optimizations
• parse transform support is better in erl_opts
• fixes to package handling
• fixes to rebar3 deps

• shell completion
• new eunit provider
• new ct provider
• well-defined hook semantics
• dependency hook and plugin support
• plugins can add source dependency types
• better namespace resolution in do and help