Revert breaking change to prefix

action.yml

@@ -14,7 +14,9 @@ inputs:
   prefix:
     required: false
     description: |-
-      One or more newline deliminated prefixes for returned tags.
+      One or more whitespace or comma deliminated prefixes for returned tags.
+      Use of separators besides new lines is deprecated but for now still
+      supported.
 
       All permutations of prefixes and suffixes are considered.
     default: ""

src/index.js

@@ -181,19 +181,27 @@ async function run() {
     const defaultTag = core.getInput("defaultTag");
     const branchRegex = core.getInput("branchRegex");
 
-    function check_prefix_suffix(input_name, input_value) {
+    function check_prefix_suffix(input_name, input_value, just_warn) {
       // Partial check that prefix and suffix inputs are OK
       // Check if there is any whitespace characters besides new lines or
       // commas.
       const re = new RegExp(/^[^\s,]+$/g);
       if (re.test(input_value.replace("\n", ""))) {
-        throw new Error(
-          `Input ${input_name} invalid, contains either comma or whitespace besides the new line separator`,
-        );
+        if (just_warn) {
+          core.warning(
+            "Input 'prefix' will soon require the use of new lines to separate prefixes, trim away your other whitespace and commas.",
+          );
+        } else {
+          throw new Error(
+            `Input ${input_name} invalid, contains either comma or whitespace besides the new line separator`,
+          );
+        }
       }
     }
-    check_prefix_suffix("prefix", prefix);
-    check_prefix_suffix("suffix", suffix);
+    // prefix and suffix has different whitespace separators, we are deprecating
+    // prefix's separators besides new lines
+    check_prefix_suffix("prefix", suffix, true);
+    check_prefix_suffix("suffix", suffix, false);
 
     core.debug(JSON.stringify(github.context));
     const allTags = await calculateTags({