Description of problem:
when a file needs to be re-opened O_APPEND and O_EXCL
flags are not filtered in EC.
- O_APPEND should be filtered because EC doesn't send O_APPEND below EC for
open to make sure writes happen on the individual fragments instead of at the
end of the file.
- O_EXCL should be filtered because shd could have created the file so even
without O_EXCL open should succeed.
Filter out these two flags in reopen.
Version-Release number of selected component (if applicable):
Found while reading code.
Steps to Reproduce:
REVIEW: https://review.gluster.org/23121 (cluster/ec: Fix reopen flags to avoid misbehavior) merged (#4) on master by Pranith Kumar Karampuri