fix Changelog after BundleInstall! on windows

- add /d switch to cd command to perform drive change
- enclose joined commands with quotes

autoload/vundle/scripts.vim

@@ -39,9 +39,17 @@ func! s:create_changelog() abort
     let updated_sha = bundle_data[1]
     let bundle      = bundle_data[2]
 
-    let updates = system('cd '.shellescape(bundle.path()).
+    let cmd = 'cd '.shellescape(bundle.path()).
           \              ' && git log --pretty=format:"%s   %an, %ar" --graph '.
-          \               initial_sha.'..'.updated_sha)
+          \               initial_sha.'..'.updated_sha
+
+    if (has('win32') || has('win64'))
+      let cmd = substitute(cmd, '^cd ','cd /d ','')  " add /d switch to change drives
+      let cmd = '"'.cmd.'"'                          " enclose in quotes
+    endif
+
+    let updates = system(cmd)
+
     call add(g:vundle_changelog, '')
     call add(g:vundle_changelog, 'Updated Bundle: '.bundle.name)