tests: fix up some import statements caught by Python 3

I'm curious how the import checker manages to be so much more
pedantic in Python 3, but not enough to bother exploring.

Differential Revision: https://phab.mercurial-scm.org/D5240

tests/test-remotefilelog-bundle2-legacy.t

@@ -6,8 +6,8 b''
 generaldelta to generaldelta interactions with bundle2 but legacy clients
 without changegroup2 support
   $ cat > testcg2.py << EOF
+  > import sys
   > from mercurial import changegroup, registrar, util
-  > import sys
   > cmdtable = {}
   > command = registrar.command(cmdtable)
   > @command('testcg2', norepo=True)
@@ -22,7 +22,7 b' without changegroup2 support'
   $ hg testcg2 || exit 80
 
   $ cat > disablecg2.py << EOF
-  > from mercurial import changegroup, util, error
+  > from mercurial import changegroup, error, util
   > deleted = False
   > def reposetup(ui, repo):
   >     global deleted

tests/test-remotefilelog-cacheprocess.t

@@ -16,7 +16,9 b''
   $ cd ..
 
   $ cat > cacheprocess-logger.py <<EOF
-  > import sys, os, shutil
+  > import os
+  > import shutil
+  > import sys
   > f = open('$TESTTMP/cachelog.log', 'w')
   > srccache = os.path.join('$TESTTMP', 'oldhgcache')
   > def log(message):