portability fixes for some tests

Apparently the ls on OS X 10.3.9 exits with success even if the file
given on the command line doesn't exist

tests/test-bad-pull

@@ -2,7 +2,7 b''
 
 hg clone http://localhost:20059/ copy
 echo $?
-ls copy 2>/dev/null || echo copy: No such file or directory
+test -e copy || echo copy: No such file or directory
 
 cat > dumb.py <<EOF
 import BaseHTTPServer, SimpleHTTPServer, signal

tests/test-empty-dir

@@ -11,6 +11,6 b' hg commit -m "second" -d "1000000 0" sub'
 cat sub/b
 hg co 0
 cat sub/b 2>/dev/null || echo "sub/b not present"
-ls sub 2>/dev/null || echo "sub not present"
+test -e sub || echo "sub not present"
 
 true

tests/test-static-http

@@ -2,7 +2,7 b''
 
 http_proxy= hg clone static-http://localhost:20059/ copy
 echo $?
-ls copy 2>/dev/null || echo copy: No such file or directory
+test -e copy || echo copy: No such file or directory
 
 # This server doesn't do range requests so it's basically only good for
 # one pull