[release-tools] Fix v8rel in branch period.

In case the v8 revision in chromium was set to an older
revision that's not in the list of recent v8 releases, the
script will bail out too early. This changes iterates over
10 more revisions, which should cover all exceeding revisions
in branch period.

NOTRY=true
TBR=hablich@chromium.org

Review URL: https://codereview.chromium.org/1067793002

Cr-Commit-Position: refs/heads/master@{#27622}

tools/release/releases.py

@@ -359,6 +359,7 @@ class RetrieveChromiumV8Releases(Step):
     releases_dict = dict((r["revision_git"], r) for r in self["releases"])
 
     cr_releases = []
+    count_past_last_v8 = 0
     try:
       for git_hash in self.GitLog(
           format="%H", grep="V8", cwd=cwd).splitlines():
@@ -374,10 +375,17 @@ class RetrieveChromiumV8Releases(Step):
             v8_hsh = match.group(1)
             cr_releases.append([cr_rev, v8_hsh])
 
+          if count_past_last_v8:
+            count_past_last_v8 += 1  # pragma: no cover
+
+          if count_past_last_v8 > 10:
+            break  # pragma: no cover
+
           # Stop as soon as we find a v8 revision that we didn't fetch in the
           # v8-revision-retrieval part above (i.e. a revision that's too old).
+          # Just iterate a few more times in case there were reverts.
           if v8_hsh not in releases_dict:
-            break  # pragma: no cover
+            count_past_last_v8 += 1  # pragma: no cover
 
     # Allow Ctrl-C interrupt.
     except (KeyboardInterrupt, SystemExit):  # pragma: no cover
@@ -414,6 +422,7 @@ class RietrieveChromiumBranches(Step):
     branches = sorted(branches, reverse=True)
 
     cr_branches = []
+    count_past_last_v8 = 0
     try:
       for branch in branches:
         if not self.GitCheckoutFileSafe("DEPS",
@@ -426,10 +435,17 @@ class RietrieveChromiumBranches(Step):
           v8_hsh = match.group(1)
           cr_branches.append([str(branch), v8_hsh])
 
+          if count_past_last_v8:
+            count_past_last_v8 += 1  # pragma: no cover
+
+          if count_past_last_v8 > 10:
+            break  # pragma: no cover
+
           # Stop as soon as we find a v8 revision that we didn't fetch in the
           # v8-revision-retrieval part above (i.e. a revision that's too old).
+          # Just iterate a few more times in case there were reverts.
           if v8_hsh not in releases_dict:
-            break  # pragma: no cover
+            count_past_last_v8 += 1  # pragma: no cover
 
     # Allow Ctrl-C interrupt.
     except (KeyboardInterrupt, SystemExit):  # pragma: no cover