test-fix-path: avoid a test hang on Windows

Windows can't typically invoke `*.py` directly as a command, and will instead
show a prompt asking what program should be used to open the file.  We can't
directly invoke the interpreter as is usually done in this case, because the
whole point is to run something not in `PATH`.  The easiest thing to do is
invoke a *.bat file that runs the interpreter.  We can get away with this
because the current implementation is to effectively run `cmd.exe /c %command%`,
which doesn't need the file extension specified.

tests/test-fix-path.t

@@ -20,8 +20,17 approximates the behavior of code format
   >   return re.sub(b' +', b' ', text.upper())
   > stdout.write(format(stdin.read()))
   > EOF
+
   $ chmod +x some/dir/uppercase.py
 
+#if windows
+  $ cat > some/dir/uppercase.bat <<EOF
+  > @echo off
+  > "$PYTHON" "$TESTTMP/test-repo/some/dir/uppercase.py"
+  > EOF
+#else
+  $ mv some/dir/uppercase.py some/dir/uppercase
+#endif
 
   $ echo babar > babar.txt
   $ hg add babar.txt
@@ -36,7 +45,7 Using absolute paths
   > evolution.allowunstable=True
   > [fix]
   > extra-bin-paths=$TESTTMP/test-repo/some/dir/
-  > uppercase-whole-file:command=uppercase.py
+  > uppercase-whole-file:command=uppercase
   > uppercase-whole-file:pattern=set:**.txt
   > EOF