Make --cache-show output deterministic

This makes sure things don't jump around in the regenerated docs.

_pytest/cacheprovider.py

@@ -219,7 +219,7 @@ def cacheshow(config, session):
     basedir = config.cache._cachedir
     vdir = basedir.join("v")
     tw.sep("-", "cache values")
-    for valpath in vdir.visit(lambda x: x.isfile()):
+    for valpath in sorted(vdir.visit(lambda x: x.isfile())):
         key = valpath.relto(vdir).replace(valpath.sep, "/")
         val = config.cache.get(key, dummy)
         if val is dummy:
@@ -235,7 +235,7 @@ def cacheshow(config, session):
     ddir = basedir.join("d")
     if ddir.isdir() and ddir.listdir():
         tw.sep("-", "cache directories")
-        for p in basedir.join("d").visit():
+        for p in sorted(basedir.join("d").visit()):
             #if p.check(dir=1):
             #    print("%s/" % p.relto(basedir))
             if p.isfile():

doc/en/cache.rst

@@ -231,10 +231,10 @@ You can always peek at the content of the cache using the
     rootdir: $REGENDOC_TMPDIR, inifile:
     cachedir: $REGENDOC_TMPDIR/.cache
     ------------------------------- cache values -------------------------------
-    example/value contains:
-      42
     cache/lastfailed contains:
       {'test_caching.py::test_function': True}
+    example/value contains:
+      42
     
     ======= no tests ran in 0.12 seconds ========