tests: pass "rev" argument to commands.update() as string

commands.update() normally gets its "rev" argument as a string, but
test-basic.t was passing an integer. That happened to work, but we
shouldn't rely on it.

Differential Revision: https://phab.mercurial-scm.org/D3851

tests/test-basic.t

@@ -1,103 +1,103 b''
 Create a repository:
 
 #if no-extraextensions
   $ hg config
   devel.all-warnings=true
   devel.default-date=0 0
   extensions.fsmonitor= (fsmonitor !)
   largefiles.usercache=$TESTTMP/.cache/largefiles
   lfs.usercache=$TESTTMP/.cache/lfs
   ui.slash=True
   ui.interactive=False
   ui.mergemarkers=detailed
   ui.promptecho=True
   web.address=localhost
   web\.ipv6=(?:True|False) (re)
   web.server-header=testing stub value
 #endif
 
   $ hg init t
   $ cd t
 
 Prepare a changeset:
 
   $ echo a > a
   $ hg add a
 
   $ hg status
   A a
 
 Writes to stdio succeed and fail appropriately
 
 #if devfull
   $ hg status 2>/dev/full
   A a
 
   $ hg status >/dev/full
   abort: No space left on device
   [255]
 #endif
 
 #if devfull
   $ hg status >/dev/full 2>&1
   [255]
 
   $ hg status ENOENT 2>/dev/full
   [255]
 #endif
 
   $ hg commit -m test
 
 This command is ancient:
 
   $ hg history
   changeset:   0:acb14030fe0a
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     test
   
 
 Verify that updating to revision 0 via commands.update() works properly
 
   $ cat <<EOF > update_to_rev0.py
   > from mercurial import ui, hg, commands
   > myui = ui.ui.load()
   > repo = hg.repository(myui, path=b'.')
-  > commands.update(myui, repo, rev=0)
+  > commands.update(myui, repo, rev=b"0")
   > EOF
   $ hg up null
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ $PYTHON ./update_to_rev0.py
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg identify -n
   0
 
 
 Poke around at hashes:
 
   $ hg manifest --debug
   b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a
 
   $ hg cat a
   a
 
 Verify should succeed:
 
   $ hg verify
   checking changesets
   checking manifests
   crosschecking files in changesets and manifests
   checking files
   1 files, 1 changesets, 1 total revisions
 
 Repository root:
 
   $ hg root
   $TESTTMP/t
   $ hg log -l1 -T '{reporoot}\n'
   $TESTTMP/t
 
 At the end...
 
   $ cd ..