vim-patch:8.2.0215: wrong file name shortening

Problem:    Wrong file name shortening. (Ingo Karkat)
Solution:   Better check for path separator. (Yasuhiro Matsumoto,
            closes vim/vim#5583, closes vim/vim#5584)
https://github.com/vim/vim/commit/a78e9c61a0ded9c5302bc77e889aa1b3d3467f61

2 files changed, 13 insertions, 8 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 70909b46cb..0fe928beb7 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -10725,14 +10725,17 @@ repeat:
         // even though the path does not have a prefix.
         if (fnamencmp(p, dirname, namelen) == 0) {
           p += namelen;
-          while (*p && vim_ispathsep(*p)) {
-            ++p;
-          }
-          *fnamep = p;
-          if (pbuf != NULL) {
-            xfree(*bufp);               // free any allocated file name
-            *bufp = pbuf;
-            pbuf = NULL;
+          if (vim_ispathsep(*p)) {
+            while (*p && vim_ispathsep(*p)) {
+              p++;
+            }
+            *fnamep = p;
+            if (pbuf != NULL) {
+              // free any allocated file name
+              xfree(*bufp);
+              *bufp = pbuf;
+              pbuf = NULL;
+            }
           }
         }
       } else {
diff --git a/src/nvim/testdir/test_fnamemodify.vim b/src/nvim/testdir/test_fnamemodify.vim
index e8fad397c3..ca17be41ec 100644
--- a/src/nvim/testdir/test_fnamemodify.vim
+++ b/src/nvim/testdir/test_fnamemodify.vim
@@ -36,6 +36,8 @@ func Test_fnamemodify()
   call chdir($HOME . '/XXXXXXXX/a/')
   call assert_equal('foo', fnamemodify($HOME . '/XXXXXXXX/a/foo', ':p:~:.'))
   call assert_equal('~/XXXXXXXX/b/foo', fnamemodify($HOME . '/XXXXXXXX/b/foo', ':p:~:.'))
+  call mkdir($HOME . '/XXXXXXXX/a.ext', 'p')
+  call assert_equal('~/XXXXXXXX/a.ext/foo', fnamemodify($HOME . '/XXXXXXXX/a.ext/foo', ':p:~:.'))
   call chdir(cwd)
   call delete($HOME . '/XXXXXXXX', 'rf')