subrepo: add include/exclude support for diffing git subrepos

Previously, git subrepos were ignored if any type of path selection
was done.
This can be solved by using subrepo status and filtering matching files.

mercurial/subrepo.py

@@ -1779,17 +1779,15 b' class gitsubrepo(abstractsubrepo):'
         if node2:
             cmd.append(node2)
 
-        if match.anypats():
-            return #No support for include/exclude yet
-
         output = ""
         if match.always():
             output += self._gitcommand(cmd) + '\n'
-        elif match.files():
-            for f in match.files():
-                output += self._gitcommand(cmd + [f]) + '\n'
-        elif match(gitprefix): #Subrepo is matched
-            output += self._gitcommand(cmd) + '\n'
+        else:
+            st = self.status(node2)[:3]
+            files = [f for sublist in st for f in sublist]
+            for f in files:
+                if match(f):
+                    output += self._gitcommand(cmd + ['--', f]) + '\n'
 
         if output.strip():
             ui.write(output)

tests/test-subrepo-git.t

@@ -785,9 +785,57 b' the output contains a regex, because git'
   \s*foobar |\s*2 +- (re)
    2 files changed, 2 insertions\(\+\), 1 deletions?\(-\) (re)
 
-ensure adding include/exclude ignores the subrepo
+adding an include should ignore the other elements
   $ hg diff --subrepos -I s/foobar
+  diff --git a/s/foobar b/s/foobar
+  index 8a5a5e2..bd5812a 100644
+  --- a/s/foobar
+  +++ b/s/foobar
+  @@ -1,4 +1,4 @@
+  -woopwoop
+  +woop    woop
+   
+   foo
+   bar
+
+adding an exclude should ignore this element
   $ hg diff --subrepos -X s/foobar
+  diff --git a/s/barfoo b/s/barfoo
+  new file mode 100644
+  index 0000000..257cc56
+  --- /dev/null
+  +++ b/s/barfoo
+  @@ -0,0 +1 @@
+  +foo
+
+moving a file should show a removal and an add
+  $ hg revert --all
+  reverting subrepo ../gitroot
+  $ cd s
+  $ git mv foobar woop
+  $ cd ..
+  $ hg diff --subrepos
+  diff --git a/s/foobar b/s/foobar
+  deleted file mode 100644
+  index 8a5a5e2..0000000
+  --- a/s/foobar
+  +++ /dev/null
+  @@ -1,4 +0,0 @@
+  -woopwoop
+  -
+  -foo
+  -bar
+  diff --git a/s/woop b/s/woop
+  new file mode 100644
+  index 0000000..8a5a5e2
+  --- /dev/null
+  +++ b/s/woop
+  @@ -0,0 +1,4 @@
+  +woopwoop
+  +
+  +foo
+  +bar
+  $ rm s/woop
 
 revert the subrepository
   $ hg revert --all