Refactor getChangesSinceMergeBase() code

src/git.ts

@@ -64,28 +64,25 @@ export async function getChangesSinceMergeBase(base: string, initialFetchDepth:
   let noMergeBase = false
   core.startGroup(`Searching for merge-base ${baseRef}...${HEAD}`)
   try {
-    let init = true
-    let lastCommitCount = await getCommitCount()
-    let depth = Math.max(lastCommitCount * 2, initialFetchDepth)
-    while (!(await hasMergeBase())) {
-      if (init) {
-        await exec('git', ['fetch', `--depth=${depth}`, 'origin', base, HEAD])
-        init = false
-      } else {
+    if (!(await hasMergeBase())) {
+      await exec('git', ['fetch', `--depth=${initialFetchDepth}`, 'origin', base, HEAD])
+      let depth = initialFetchDepth
+      let lastCommitCount = await getCommitCount()
+      while (!(await hasMergeBase())) {
+        depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER)
         await exec('git', ['fetch', `--deepen=${depth}`, 'origin', base, HEAD])
-      }
-      const commitCount = await getCommitCount()
-      if (commitCount === lastCommitCount) {
-        core.info('No more commits were fetched')
-        core.info('Last attempt will be to fetch full history')
-        await exec('git', ['fetch'])
-        if (!(await hasMergeBase())) {
-          noMergeBase = true
+        const commitCount = await getCommitCount()
+        if (commitCount === lastCommitCount) {
+          core.info('No more commits were fetched')
+          core.info('Last attempt will be to fetch full history')
+          await exec('git', ['fetch'])
+          if (!(await hasMergeBase())) {
+            noMergeBase = true
+          }
+          break
         }
-        break
+        lastCommitCount = commitCount
       }
-      depth = Math.min(depth * 2, Number.MAX_SAFE_INTEGER)
-      lastCommitCount = commitCount
     }
   } finally {
     core.endGroup()