tests: conditonalize a difference in test-merge-tools.t on Windows

tests/test-merge-tools.t

@@ -1957,7 +1957,8 b' Check that the extra information is prin'
   >   --config 'templatealias.extmerge_section(sect)="- {pad("{sect.name} ({sect.label})", 20, left=True)}: {revset(sect.node)%"{rev}:{shortest(node,8)} {desc|firstline} {separate(" ", tags, bookmarks, branch)}"}"'
   merging b
   
-  Running merge tool for b (*/bin/echo): (glob)
+  Running merge tool for b ("*/bin/echo.exe"): (glob) (windows !)
+  Running merge tool for b (*/bin/echo): (glob) (no-windows !)
   - local (working copy): 10:2d1f533d add binary file (#2) tip default
   -          base (base): -1:00000000  default
   -    other (merge rev): 9:1e7ad7d7 add binary file (#1) default