Issue #3160015 by quietone, mikelutz: Don't remove all slashes from filepath in file.php

(cherry picked from commit 6e1d970a)

core/modules/file/src/Plugin/migrate/source/d7/File.php

@@ -88,7 +88,7 @@ public function prepareRow(Row $row) {
     // At this point, $path could be an absolute path or a relative path,
     // depending on how the scheme's variable was set. So we need to shear out
     // the source_base_path in order to make them all relative.
-    $path = str_replace($this->configuration['constants']['source_base_path'], NULL, $path);
+    $path = preg_replace('#' . preg_quote($this->configuration['constants']['source_base_path']) . '#', '', $path, 1);
     $row->setSourceProperty('filepath', $path);
     return parent::prepareRow($row);
   }

core/modules/file/tests/src/Kernel/Plugin/migrate/source/d7/FileTest.php

@@ -158,6 +158,36 @@ public function providerSource() {
       'scheme' => 'public',
     ];
 
+    // Test getting only private files with absolute file private path.
+    $tests[3]['source_data'] = $tests[0]['source_data'];
+    $tests[3]['source_data']['variable'][1] = [
+      'name' => 'file_private_path',
+      'value' => serialize('/home/lillian/subdomains/u2/u2-private-files'),
+    ];
+    $tests[3]['expected_data'] = [
+      [
+        'fid' => '1',
+        'uid' => '1',
+        'filename' => 'cube.jpeg',
+        'uri' => 'private://cube.jpeg',
+        'filemime' => 'image/jpeg',
+        'filesize' => '3620',
+        'status' => '1',
+        'timestamp' => '1421727515',
+        'filepath' => 'home/lillian/subdomains/u2/u2-private-files/cube.jpeg',
+      ],
+    ];
+    // Do an automatic count.
+    $tests[3]['expected_count'] = NULL;
+
+    // Set up plugin configuration.
+    $tests[3]['configuration'] = [
+      'constants' => [
+        'source_base_path' => '/',
+      ],
+      'scheme' => 'private',
+    ];
+
     return $tests;
   }