registrar: clarify the documentation about some byte strings being required

I *thought* these needed to be byte strings, but didn't remember and had to
search out examples.

Differential Revision: https://phab.mercurial-scm.org/D9489

mercurial/registrar.py

@@ -37,7 +37,7 b' class _funcregistrarbase(object):'
 
         keyword = registrar.keyword()
 
-        @keyword('bar')
+        @keyword(b'bar')
         def barfunc(*args, **kwargs):
             '''Explanation of bar keyword ....
             '''
@@ -249,7 +249,7 b' class revsetpredicate(_funcregistrarbase'
 
         revsetpredicate = registrar.revsetpredicate()
 
-        @revsetpredicate('mypredicate(arg1, arg2[, arg3])')
+        @revsetpredicate(b'mypredicate(arg1, arg2[, arg3])')
         def mypredicatefunc(repo, subset, x):
             '''Explanation of this revset predicate ....
             '''
@@ -299,7 +299,7 b' class filesetpredicate(_funcregistrarbas'
 
         filesetpredicate = registrar.filesetpredicate()
 
-        @filesetpredicate('mypredicate()')
+        @filesetpredicate(b'mypredicate()')
         def mypredicatefunc(mctx, x):
             '''Explanation of this fileset predicate ....
             '''
@@ -356,7 +356,7 b' class templatekeyword(_templateregistrar'
         templatekeyword = registrar.templatekeyword()
 
         # new API (since Mercurial 4.6)
-        @templatekeyword('mykeyword', requires={'repo', 'ctx'})
+        @templatekeyword(b'mykeyword', requires={b'repo', b'ctx'})
         def mykeywordfunc(context, mapping):
             '''Explanation of this template keyword ....
             '''
@@ -388,7 +388,7 b' class templatefilter(_templateregistrarb'
 
         templatefilter = registrar.templatefilter()
 
-        @templatefilter('myfilter', intype=bytes)
+        @templatefilter(b'myfilter', intype=bytes)
         def myfilterfunc(text):
             '''Explanation of this template filter ....
             '''
@@ -420,8 +420,8 b' class templatefunc(_templateregistrarbas'
 
         templatefunc = registrar.templatefunc()
 
-        @templatefunc('myfunc(arg1, arg2[, arg3])', argspec='arg1 arg2 arg3',
-                      requires={'ctx'})
+        @templatefunc(b'myfunc(arg1, arg2[, arg3])', argspec=b'arg1 arg2 arg3',
+                      requires={b'ctx'})
         def myfuncfunc(context, mapping, args):
             '''Explanation of this template function ....
             '''
@@ -460,7 +460,7 b' class internalmerge(_funcregistrarbase):'
 
         internalmerge = registrar.internalmerge()
 
-        @internalmerge('mymerge', internalmerge.mergeonly,
+        @internalmerge(b'mymerge', internalmerge.mergeonly,
                        onfailure=None, precheck=None,
                        binary=False, symlink=False):
         def mymergefunc(repo, mynode, orig, fcd, fco, fca,