test:exists: add relative file case

Author: scivision

test/TestFileImpure.m

@@ -5,7 +5,7 @@
 end
 
 properties(TestParameter)
-p_exists = {{pwd(), true}, {mfilename("fullpath") + ".m", true}, {tempname, false}}
+p_exists = {{pwd(), true}, {mfilename("fullpath") + ".m", true}, {stdlib.filename(mfilename("fullpath") + ".m"), true} {tempname, false}}
 % on CI matlabroot can be writable!
 in_is_write = {pwd(), "not-exists"};
 ref_is_write = {true, false}