release-version.sh: verify that maven-release-plugin did its job

Under circumstances yet to be determined, maven-release-plugin fails to
adjust the <version> tag to the correct release version, then fails to
notice that and make an incorrect tag (still referencing the SNAPSHOT
version), and finally fails to commit and push changes bumping to the next
release cycle.

Detect that situation and fail.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

release-version.sh

@@ -123,7 +123,11 @@ $DRY_RUN mvn $BATCH_MODE release:prepare -DpushChanges=false -Dresume=false $TAG
         $PROFILE $DEV_VERSION -DreleaseVersion="$VERSION" \
 	"-Darguments=${EXTRA_ARGS# }" &&
 
-# Squash the two commits on the current branch into one
+# Squash the two commits on the current branch produced by the
+# maven-release-plugin into one
+test "[maven-release-plugin] prepare for next development iteration" = \
+	"$(git show -s --format=%s HEAD)" ||
+die "maven-release-plugin's commits are unexpectedly missing!"
 $DRY_RUN git reset --soft HEAD^^ &&
 if ! git diff-index --cached --quiet --ignore-submodules HEAD --
 then