ci: stop cancelling master runs, and revert the release job conditions

The empty homebrew tap was never a condition problem. The release job ran, the
matrix built all six targets, and the tap step then failed with "Input required
and not supplied: token" because HOMEBREW_TAP_TOKEN resolves to an empty
string. Four rounds of edits to those `if` expressions chased a symptom, so
they go back to what they were.

What stays is the CI concurrency change: a cancelled master run leaves the
release gate waiting on a CI run for a commit nothing will push again.

.github/workflows/ci.yml

@@ -9,10 +9,6 @@ on:
   pull_request:
     branches: ['**']
 
-# Superseding a branch run saves the matrix from running twice, but a master run
-# must be allowed to finish: the release workflow gates on finding a completed
-# CI run for its own commit, and nothing ever pushes that commit again. A
-# cancelled run there strands the release until it times out.
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: ${{ github.ref != 'refs/heads/master' }}

.github/workflows/release.yml

@@ -128,14 +128,6 @@ jobs:
           # refuse anything that is not a literal version tag.
           [[ "$tag" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-[0-9A-Za-z.-]+)?$ ]] || { echo "::error::unexpected tag: $tag"; exit 1; }
           echo "tag=$tag" >> "$GITHUB_OUTPUT"
-          echo "resolved tag: '$tag'"
-
-      # The downstream jobs gate on these, and a silent empty value here cost
-      # four release runs, so say them out loud.
-      - name: Report what the downstream jobs will see
-        run: |
-          echo "created = '${{ steps.release-plz.outputs.releases_created }}'"
-          echo "tag     = '${{ steps.tag.outputs.tag }}'"
 
   # Attaches downloadable binaries to the release GitHub just created, or to an
   # existing tag when dispatched manually with `tag` (recovering a target that
@@ -143,13 +135,7 @@ jobs:
   binaries:
     name: ${{ matrix.target }}
     needs: release
-    # `github.event_name` is the one context proven to evaluate here: ci-gate
+    if: needs.release.outputs.created == 'true' || inputs.tag != ''
-    # uses it and skips correctly on dispatch. `inputs.tag`,
-    # `github.event.inputs.tag` and `needs.release.outputs.tag` were all tried
-    # and all left this job skipped, which is how v7.0.0 shipped to crates.io
-    # with an empty homebrew tap. A dispatch without a tag now fails loudly in
-    # the checkout below rather than skipping in silence.
-    if: needs.release.outputs.created == 'true' || github.event_name == 'workflow_dispatch'
     runs-on: ${{ matrix.os }}
     strategy:
       # One flaky cross-linker must not hold back the five targets that built.
@@ -206,7 +192,7 @@ jobs:
   homebrew:
     name: Homebrew tap
     needs: [release, binaries]
-    if: needs.release.outputs.created == 'true' || github.event_name == 'workflow_dispatch'
+    if: needs.release.outputs.created == 'true' || inputs.tag != ''
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4