CI: Improve tag detection for docker builds (#3066)

Since moving to hatch-vcs and the next version strategies of
`setuptools_scm`, the default behavior of a new branch is to increment
the minor version (or major, if the new year happens to have come). At
the same time, we have rules where `docker/XYZ` produces a docker tag
`nipreps/fmriprep:XYZ`.

To create a Docker branch that indicates a patch on a minor series,
which will be useful for reusing work directories and testing patches
before a bug-fix release, this change allows for branches named
`docker/X.Y.x+tag`. For example, `docker/23.1.x+mynewpatch` would
produce a version `23.1.5.devN+gHASH` and a Docker image
`nipreps/fmriprep:mynewpatch`.

Author: effigies

.circleci/config.yml

@@ -854,8 +854,10 @@ jobs:
           name: Deploy to Docker Hub
           no_output_timeout: 40m
           command: |
-            docker tag nipreps/fmriprep nipreps/fmriprep:${CIRCLE_BRANCH#docker/}
-            docker push nipreps/fmriprep:${CIRCLE_BRANCH#docker/}
+            # Format: docker/[<version-like>+]<tag> -> nipreps/fmriprep:<tag>
+            # <version-like>+<tag> guides setuptools_scm to get the right major/minor
+            docker tag nipreps/fmriprep nipreps/fmriprep:${CIRCLE_BRANCH##*[/+]}
+            docker push nipreps/fmriprep:${CIRCLE_BRANCH##*[/+]}
 
   deploy_docker:
     <<: *machine_defaults