diffstat: fix parsing of filenames with spaces

The patch changes the output of "hg diff --stat" when one file whose filename
has spaces has changed, making it get the full filename instead of just the
substring between the last space and the end of the filename.

It also changes the diffstat generated by "hg email -d" when one of the commit
messages starts with "diff". Because of the regex used to parse the filename,
the diffstat generated by "hg email -d" will still be not correct if a commit
message starts with "diff -r ".

Before the patch Mercurial has the following behavior:

$ echo "foobar">"file with spaces"
$ hg add "file with spaces"
$ hg diff --stat
 spaces |  1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
$ hg diff --git --stat
 file with spaces |  1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

After the patch:

$ echo "foobar">"file with spaces"
$ hg add "file with spaces"
$ hg diff --stat
 file with spaces |  1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
$ hg diff --git --stat
 file with spaces |  1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

Before the patch:

$ hg add mercurial/patch.py tests/tests-diffstat.t
$ hg commit -m "diffstat: fix parsing of filenames"

$ hg email -d --test tip
This patch series consists of 1 patches.

diffstat: fix parsing of filenames
[...]

 filenames             |    0
 mercurial/patch.py    |    6 ++++--
 tests/test-diffstat.t |   17 +++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)
[...]

After the patch:

$ hg email -d --test tip
This patch series consists of 1 patches.

diffstat: fix parsing of filenames

[...]

 mercurial/patch.py    |    6 ++++--
 tests/test-diffstat.t |   17 +++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)
[...]

mercurial/patch.py

@@ -1529,6 +1529,8 b' def trydiff(repo, revs, ctx1, ctx2, modi'
                 yield text
 
 def diffstatdata(lines):
+    diffre = re.compile('^diff .*-r [a-z0-9]+\s(.*)$')
+
     filename, adds, removes = None, 0, 0
     for line in lines:
         if line.startswith('diff'):
@@ -1539,9 +1541,9 b' def diffstatdata(lines):'
             adds, removes = 0, 0
             if line.startswith('diff --git'):
                 filename = gitre.search(line).group(1)
-            else:
+            elif line.startswith('diff -r'):
                 # format: "diff -r ... -r ... filename"
-                filename = line.split(None, 5)[-1]
+                filename = diffre.search(line).group(1)
         elif line.startswith('+') and not line.startswith('+++'):
             adds += 1
         elif line.startswith('-') and not line.startswith('---'):

tests/test-diffstat.t

@@ -46,3 +46,20 b' Binary git diffstat:'
    b |  Bin 
    1 files changed, 0 insertions(+), 0 deletions(-)
 
+  $ hg ci -m createb
+
+  $ printf '\0' > "file with spaces"
+  $ hg add "file with spaces"
+
+Filename with spaces diffstat:
+
+  $ hg diff --stat
+   file with spaces |    0 
+   1 files changed, 0 insertions(+), 0 deletions(-)
+
+Filename with spaces git diffstat:
+
+  $ hg diff --stat --git
+   file with spaces |  Bin 
+   1 files changed, 0 insertions(+), 0 deletions(-)
+