From 00dfd2c8e1a63c47f20dce93e8e3e34dd1df3071 Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Wed, 11 Nov 2020 11:57:08 +0100
Subject: [PATCH] Fix lock file being parsed when not strictly needed, fixes
 #9452

---
 src/Composer/Installer.php | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/Composer/Installer.php b/src/Composer/Installer.php
index 0586e261c..7b1f893ae 100644
--- a/src/Composer/Installer.php
+++ b/src/Composer/Installer.php
@@ -360,8 +360,17 @@ class Installer
 
         $lockedRepository = null;
 
-        if ($this->locker->isLocked()) {
-            $lockedRepository = $this->locker->getLockedRepository(true);
+        try {
+            if ($this->locker->isLocked()) {
+                $lockedRepository = $this->locker->getLockedRepository(true);
+            }
+        } catch (\Seld\JsonLint\ParsingException $e) {
+            if ($this->updateAllowList || $this->updateMirrors) {
+                // in case we are doing a partial update or updating mirrors, the lock file is needed so we error
+                throw $e;
+            }
+            // otherwise, ignoring parse errors as the lock file will be regenerated from scratch when
+            // doing a full update
         }
 
         if ($this->updateAllowList) {