submodules avec modifiées et sans traces de contenu - pourquoi et comment le supprimer?

c'est ce que mon git status' résultat ressemble à ceci:

# On branch master
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#   (use "git checkout -- <file>..." to discard changes in working directory)
#   (commit or discard the untracked or modified content in submodules)
#
#   modified:   vim/bundle/pathogen (modified content)
#   modified:   vim/bundle/sparkup (untracked content)
#
no changes added to commit (use "git add" and/or "git commit -a")

de course git diff vim montre ceci:

diff --git a/vim/bundle/pathogen b/vim/bundle/pathogen
--- a/vim/bundle/pathogen
+++ b/vim/bundle/pathogen
@@ -1 +1 @@
-Subproject commit fcf77f5101f3e589ce006c40ad3a0432735a05cf
+Subproject commit fcf77f5101f3e589ce006c40ad3a0432735a05cf-dirty
diff --git a/vim/bundle/sparkup b/vim/bundle/sparkup
--- a/vim/bundle/sparkup
+++ b/vim/bundle/sparkup
@@ -1 +1 @@
-Subproject commit 04a81b41f116a19184359a6f8685c192f5c36c70
+Subproject commit 04a81b41f116a19184359a6f8685c192f5c36c70-dirty

Pourquoi l'un sans traces, les autres modifiés, ce qui fait la diff veux dire? Mais le plus important: comment se fait-il et comment s'en débarrasser?