[patch 03/11] stg diff / files: don't update directory cache unless needed

[Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>]

Do git-update-cache only when diffing with the working tree, not otherwise.
Spending something like 1min for a stg files is bad - yes, my laptop
was really busy and the Linux tree was probably cache-cold, but that's just
not needed.

Also, in diffstat we currently do it both by hand and by calling git.diff.
And in files there's no need at all for that - even the comments says that
"files" has only to do with committed changes.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
---

 stgit/git.py |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/stgit/git.py b/stgit/git.py
--- a/stgit/git.py
+++ b/stgit/git.py
@@ -376,11 +376,11 @@ def status(files = [], modified = False,
 def diff(files = [], rev1 = 'HEAD', rev2 = None, out_fd = None):
     """Show the diff between rev1 and rev2
     """
-    os.system('git-update-cache --refresh > /dev/null')
 
     if rev2:
         diff_str = _output(['git-diff-tree', '-p', rev1, rev2] + files)
     else:
+        os.system('git-update-cache --refresh > /dev/null')
         diff_str = _output(['git-diff-cache', '-p', rev1] + files)
 
     if out_fd:
@@ -392,7 +392,6 @@ def diffstat(files = [], rev1 = 'HEAD', 
     """Return the diffstat between rev1 and rev2
     """
 
-    os.system('git-update-cache --refresh > /dev/null')
     p=popen2.Popen3('git-apply --stat')
     diff(files, rev1, rev2, p.tochild)
     p.tochild.close()
@@ -404,7 +403,6 @@ def diffstat(files = [], rev1 = 'HEAD', 
 def files(rev1, rev2):
     """Return the files modified between rev1 and rev2
     """
-    os.system('git-update-cache --refresh > /dev/null')
 
     str = ''
     for line in _output_lines('git-diff-tree -r %s %s' % (rev1, rev2)):