git-svn testsuite: use standard configuration for Subversion tools

I have tweaked configuration in my ~/.subversion directory, namely I am
running auto-properties and automatically adding '$Id$' expansion to
every file.  This choke the last test named 'proplist' from
t9101-git-svn-props.sh, because one more property, svn:keywords is
automatically added.

I had just wrapped svn invocation with the svn_cmd that specifies empty
directory via --config-dir argument.  Since the latter is the global
option, it should be recognized by all svn subcommands, so no
regressions will be introduced.

Now svn_cmd is used everywhere, not just in the failed test module: this
should guard us from the future clashes with user-defined configuration
tweaks.

Signed-off-by: Eygene Ryabinkin <rea-git@codelabs.ru>
Acked-by: Eric Wong <normalperson@yhbt.net>

t/t9127-git-svn-partial-rebuild.sh

@@ -14,21 +14,21 @@ test_expect_success 'initialize svnrepo' '
 		cd trunk &&
 		echo foo > foo &&
 		cd .. &&
-		svn import -m "import for git-svn" . "$svnrepo" >/dev/null &&
-		svn copy "$svnrepo"/trunk "$svnrepo"/branches/a \
+		svn_cmd import -m "import for git-svn" . "$svnrepo" >/dev/null &&
+		svn_cmd copy "$svnrepo"/trunk "$svnrepo"/branches/a \
 			-m "created branch a" &&
 		cd .. &&
 		rm -rf import &&
-		svn co "$svnrepo"/trunk trunk &&
+		svn_cmd co "$svnrepo"/trunk trunk &&
 		cd trunk &&
 		echo bar >> foo &&
-		svn ci -m "updated trunk" &&
+		svn_cmd ci -m "updated trunk" &&
 		cd .. &&
-		svn co "$svnrepo"/branches/a a &&
+		svn_cmd co "$svnrepo"/branches/a a &&
 		cd a &&
 		echo baz >> a &&
-		svn add a &&
-		svn ci -m "updated a" &&
+		svn_cmd add a &&
+		svn_cmd ci -m "updated a" &&
 		cd .. &&
 		git svn init --stdlayout "$svnrepo"
 	)