Index: node_modules/tar/lib/strip-absolute-path.js
===================================================================
--- node_modules/tar/lib/strip-absolute-path.js	(revision 81bc7da776d8cda42939ef4ab350c88d13b4941f)
+++ node_modules/tar/lib/strip-absolute-path.js	(revision 81bc7da776d8cda42939ef4ab350c88d13b4941f)
@@ -0,0 +1,24 @@
+// unix absolute paths are also absolute on win32, so we use this for both
+const { isAbsolute, parse } = require('path').win32
+
+// returns [root, stripped]
+// Note that windows will think that //x/y/z/a has a "root" of //x/y, and in
+// those cases, we want to sanitize it to x/y/z/a, not z/a, so we strip /
+// explicitly if it's the first character.
+// drive-specific relative paths on Windows get their root stripped off even
+// though they are not absolute, so `c:../foo` becomes ['c:', '../foo']
+module.exports = path => {
+  let r = ''
+
+  let parsed = parse(path)
+  while (isAbsolute(path) || parsed.root) {
+    // windows will think that //x/y/z has a "root" of //x/y/
+    // but strip the //?/C:/ off of //?/C:/path
+    const root = path.charAt(0) === '/' && path.slice(0, 4) !== '//?/' ? '/'
+      : parsed.root
+    path = path.slice(root.length)
+    r += root
+    parsed = parse(path)
+  }
+  return [r, path]
+}