tests: run 'cvs init' only on non-existent directories (issue4482)

Do not create cvsroot directory since cvs-1.12 errors out
if CVSROOT exists before 'cvs init'.

tests/test-convert-cvs-branch.t

@@ -23,6 +23,7 b' create cvs repository'
   $ CVS_OPTIONS=-f
   $ export CVS_OPTIONS
   $ cd ..
+  $ rmdir cvsrepo
   $ cvscall -q -d "$CVSROOT" init
 
 Create a new project

tests/test-convert-cvs-detectmerge.t

@@ -33,7 +33,6 b' XXX copied from test-convert-cvs-synthet'
 
 create cvs repository with one project
 
-  $ mkdir cvsrepo
   $ cvscall -q -d "$CVSROOT" init
   $ mkdir cvsrepo/proj
 

tests/test-convert-cvs-synthetic.t

@@ -14,6 +14,7 b' create cvs repository with one project'
   $ CVS_OPTIONS=-f
   $ export CVS_OPTIONS
   $ cd ..
+  $ rmdir cvsrepo
   $ cvscall()
   > {
   >     cvs -f "$@"

tests/test-convert-cvs.t

@@ -33,6 +33,7 b' create cvs repository'
   $ CVS_OPTIONS=-f
   $ export CVS_OPTIONS
   $ cd ..
+  $ rmdir cvsrepo
   $ cvscall -q -d "$CVSROOT" init
 
 create source directory

tests/test-convert-cvsnt-mergepoints.t

@@ -32,6 +32,7 b' create cvs repository'
   $ CVS_OPTIONS=-f
   $ export CVS_OPTIONS
   $ cd ..
+  $ rmdir cvsmaster
   $ filterpath cvscall -Q -d "$CVSROOT" init
 
 checkout #1: add foo.txt