patch: explicitely close input patch files when leaving

If applydiff() raises an exception, the opened patch file is kept alive in the
exception context. If it is a temporary file (for instance supplied by import
command with stdin input), Windows cannot clean it up.

mercurial/patch.py

@@ -1126,6 +1126,8 b' def internalpatch(patchobj, ui, strip, c'
     finally:
         if cwd:
             os.chdir(curdir)
+        if fp != patchobj:
+            fp.close()
     if ret < 0:
         raise PatchError
     return ret > 0