Issue a warning if "-r ." is used with two working directory parents.
Rationale for not aborting instead:
The first parent is usually more important as it is the local branch
during a merge and commands like 'hg diff' and 'hg diff -r.' behave still
identically (except for the warning of course).
Added a test for log -r. with one and two parents.
% 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