test-merge-tools: windows fixes
- /bin/cat does not exist, expect 'cat'
- non-interactive mode is not correctly detected in pysh, force it
% init
adding a
% fold in the middle of the queue
now at: p1
--- a/a
+++ b/a
@@ -1,1 +1,2 @@
a
+a
p1
p3
--- a/a
+++ b/a
@@ -1,1 +1,3 @@
a
+a
+b
% fold with local changes
abort: local changes found, refresh first
--- a/a
+++ b/a
@@ -1,1 +1,3 @@
a
+a
+b