py3: add b'' prefixes in tests/test-pager.t

# skip-blame because just b'' prefixes

Differential Revision: https://phab.mercurial-scm.org/D3598

tests/test-pager.t

@@ -260,9 +260,9 b' Pager should not override the exit code '
   > from mercurial import commands, registrar
   > cmdtable = {}
   > command = registrar.command(cmdtable)
-  > @command(b'fortytwo', [], 'fortytwo', norepo=True)
+  > @command(b'fortytwo', [], b'fortytwo', norepo=True)
   > def fortytwo(ui, *opts):
-  >     ui.write('42\n')
+  >     ui.write(b'42\n')
   >     return 42
   > EOF
 
@@ -377,8 +377,8 b' During pushbuffer, pager should not star'
   $ cat > $TESTTMP/pushbufferpager.py <<EOF
   > def uisetup(ui):
   >     ui.pushbuffer()
-  >     ui.pager('mycmd')
-  >     ui.write('content\n')
+  >     ui.pager(b'mycmd')
+  >     ui.write(b'content\n')
   >     ui.write(ui.popbuffer())
   > EOF