Prevent type exception on concatenation if diffstat returns None.
This will most often occur if diffstat is not installed in the
target platform, though may also happen in other cases where
diffstat fails to execute.
Signed-off-by: Sean Dague <sean@dague.net>
% init
% commit
adding 1/base
adding 2/base
% qnew mqbase
% qrefresh
% qdiff
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% patch file contents
mqbase
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qrefresh 1
% qdiff
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% patch file contents
mqbase
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qrefresh . in subdir
% qdiff
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% patch file contents
mqbase
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qrefresh in hg-root again
% qdiff
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched
% patch file contents
mqbase
diff -r b55ecdccb5cf 1/base
--- a/1/base
+++ b/1/base
@@ -1,1 +1,1 @@ base
-base
+patched
diff -r b55ecdccb5cf 2/base
--- a/2/base
+++ b/2/base
@@ -1,1 +1,1 @@ base
-base
+patched