This is a bugfix release with the following changes or improvements:

• Our continuous integration environment has switched from Travis and
  AppVeyor to Azure Pipelines CI.

• Fix adding worktrees for bare repositories.

• Fix parsed patches not computing the old respectively new line
  numbers correctly.

• Fix parsing configuration variables which do not have a section.

• Fix a zero-byte allocation when trying to detect file renames and
  copies of a diff without any hunks.

• Fix a zero-byte allocation when trying to resize or duplicate
  vectors.

• Fix return value when trying to unlock worktrees which aren't
  locked.

• Fix returning an unitialized error code when preparing a revision
  walk without any pushed commits.

• Fix return value of git_remote_lookup when lookup of
  "remote.$remote.tagopt" fails.

• Fix the revision walk always labelling commits as interesting due
  to a mishandling of the commit date.

• Fix the packbuilder inserting uninteresting blobs when adding a
  tree containing references to such blobs.

• Ignore unsupported authentication schemes in HTTP transport.

• Improve performane of git_remote_prune.

• Fix detection of whether qsort_r has a BSD or GNU function
  signature.

• Fix detection of iconv if it is provided by libc.