windows: use abspath in commandserver

We replace `os.path.abspath` with `util.abspath`. This should solve more "drive
capitalization" issue on Windows.

Differential Revision: https://phab.mercurial-scm.org/D11061

mercurial/commandserver.py

@@ -429,7 +429,7 b' def setuplogging(ui, repo=None, fp=None)'
     elif logpath == b'-':
         logger = loggingutil.fileobjectlogger(ui.ferr, tracked)
     else:
-        logpath = os.path.abspath(util.expandpath(logpath))
+        logpath = util.abspath(util.expandpath(logpath))
         # developer config: cmdserver.max-log-files
         maxfiles = ui.configint(b'cmdserver', b'max-log-files')
         # developer config: cmdserver.max-log-size