Drupal 7 PHP extensions not available

[devekko]

since the last update of Devstep Drupal 7 install now complains on install about missing PHP extensions

there is no composer.json in Drupal 7 and these extensions below are optional extensions on Heroku

I think thats a regression since the code update

Unicode library Standard PHP
Operations on Unicode strings are emulated on a best-effort basis. Install the PHP mbstring extension for improved Unicode support.

PHP extensions  Disabled
Drupal requires you to enable the PHP extensions in the following list (see the system requirements page for more information):
gd

[devekko]

its actually upstream? Heroku Buildpack?

composer.json fixes it

{
    "require": {
        "ext-gd": "*",
        "ext-mbstring": "*"
    }
}

[fgrehm]

Hum... Is that composer.json fix also required on Heroku?