diffstat: support filenames with whitespaces on renames

This is a follow-up patch to D5628. `line.split()` cannot get filenames with
whitespaces as mentioned by @yuja. This patch replaces `split()` method with
`slice`. Corresponding tests were also added.

Differential Revision: https://phab.mercurial-scm.org/D5709

mercurial/patch.py

@@ -2806,9 +2806,9 b' def diffstatdata(lines):'
               line.startswith('Binary file')):
             isbinary = True
         elif line.startswith('rename from'):
-            filename = line.split()[-1]
+            filename = line[12:]
         elif line.startswith('rename to'):
-            filename += ' => %s' % line.split()[-1]
+            filename += ' => %s' % line[10:]
     addresult()
     return results
 

tests/test-diffstat.t

@@ -255,3 +255,19 b" When a file is renamed, --git shouldn't "
   $ hg diff --stat --git
    a => b |  0 
    1 files changed, 0 insertions(+), 0 deletions(-)
+-- filename may contain whitespaces
+  $ echo > c
+  $ hg ci -Am 'add c'
+  adding c
+  $ hg mv c 'new c'
+  $ hg diff --git
+  diff --git a/c b/new c
+  rename from c
+  rename to new c
+  $ hg diff --stat
+   c     |  1 -
+   new c |  1 +
+   2 files changed, 1 insertions(+), 1 deletions(-)
+  $ hg diff --stat --git
+   c => new c |  0 
+   1 files changed, 0 insertions(+), 0 deletions(-)