Disabling priorities allowed "yum install httpd-devel" to work.
PS: i now have priorities as
priority = 1 [base] priority = 3010 [asl-3.0] priority = 3010 [asl-3.0-testing] priority = 4020 [virtualmin] priority = 4020 [virtualmin-universal] priority = 30 [base] priority = 30 [updates] priority = 40 [extras] priority = 50 [epel] does this seem ok?