The -h option is not working in xzgrep/zgrep

Issue

• The option -h does not work with xzgrep and zgrep
• It shall suppress the filenames as it does with grep.
• According to man page, the output of xzgrep with -h option shall be as without filename prefix.

  -h, --no-filename         suppress the file name prefix on output
      --label=LABEL         use LABEL as the standard input file name prefix

• zgrep -h does not work in Red Hat Enterprise Linux 6

[root@host root]# zgrep -h foo f1 f2
f1:foo
f2:foo