IPv6 literal addresses in wsrep SST scripts

SST joiner address parsing in wsrep_sst_common script no longer works with IPv6 address literals since MariaDB 10.2.13. It used to work in MariaDB 10.2.12.

I seems problem was introduced in https://github.com/MariaDB/server/commit/e78e308e818a4a763ebb981302851f58f4c42bba.

Based on the test case included in commit message it would seem author made an assumption that IPv6 address literals will not contain colon symbols. Unfortunately enough it is not true.

Comparison of address parsing expressions:

MariaDB 10.2.13

(

  WSREP_SST_OPT_ADDR="[2001:db8::1]:4444/path";

  echo ${WSREP_SST_OPT_ADDR%%[:/]*};

)

// produces:

// [2001

MariaDB 10.2.12

(

  WSREP_SST_OPT_ADDR="[2001:db8::1]:4444/path";

  echo ${WSREP_SST_OPT_ADDR/\]*/\]};

)

// produces:

// [2001:db8::1]