Allow 0-patch version if / when a release candidate or beta exists (#102)

Author: mart-r

medcat-v2/.release/prepare_patch_release.sh

@@ -55,7 +55,14 @@ VERSION_PATCH="$(echo "$VERSION" | sed -E 's/^[0-9]+\.[0-9]+\.([0-9]+).*/\1/')"
 RELEASE_BRANCH="medcat/v$VERSION_MAJOR_MINOR"
 
 # some prerequisites
-[[ "$VERSION_PATCH" == "0" ]] && error_exit "Patch version must not be 0."
+if [[ "$VERSION_PATCH" == "$VERSION_PATCH_AND_PRERELEASE" ]]; then
+    if [[ "$VERSION_PATCH" == "0" ]]; then
+        # look for any prerelease tags on this major.minor
+        if ! git tag -l "medcat/v${VERSION_MAJOR_MINOR}.0[a-z]*" | grep -q .; then
+            error_exit "Patch version must not be 0 unless a prerelease (alpha/beta/rc) already exists."
+        fi
+    fi
+fi
 
 run_or_echo git fetch origin