php-igbinary dependency is satisfied by php-legacy-igbinary, breaking PHP with redis extension enabled

php-legacy-redis depends on php-legacy-igbinary
php-redis on php-igbinary

But a mismatch is possible, leading to a broken PHP installation.

[0] # pacman -Ss ...  
extra/php-legacy-redis 6.0.2-3 [installed]
extra/php-redis 6.0.2-3 [installed]
extra/php-igbinary 3.2.15-3
extra/php-legacy-igbinary 3.2.15-3 [installed]

[0] # pacman -R php-legacy-igbinary
checking dependencies...
error: failed to prepare transaction (could not satisfy dependencies)
:: removing php-legacy-igbinary breaks dependency 'php-legacy-igbinary' required by php-legacy-redis
:: removing php-legacy-igbinary breaks dependency 'php-igbinary' required by php-redis

[1] # php -v                       
PHP Warning:  PHP Startup: Unable to load dynamic library 'redis' (tried: /usr/lib/php/modules/redis (/usr/lib/php/modules/redis: cannot open shared object file: No such file or directory), /usr/lib/php/modules/redis.so (/usr/lib/php/modules/redis.so: undefined symbol: igbinary_serialize)) in Unknown on line 0
...