[DRE-maint] Bug#890699: ruby-rspec-rails: FTBFS and Debci failure with ruby-rspec 3.7.0c1e0m0s1-1

[Adrian Bunk]

Source: ruby-rspec-rails
Version: 3.5.2-1
Severity: serious
Tags: buster sid

https://ci.debian.net/packages/r/ruby-rspec-rails/unstable/amd64/
https://tests.reproducible-builds.org/debian/rb-pkg/unstable/amd64/ruby-rspec-rails.html

...
┌──────────────────────────────────────────────────────────────────────────────┐
│ Checking Rubygems dependency resolution on ruby2.3                           │
└──────────────────────────────────────────────────────────────────────────────┘

sh: 1: git: not found
GEM_PATH=debian/ruby-rspec-rails/usr/share/rubygems-integration/all:/var/lib/gems/2.3.0:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.3.0:/usr/share/rubygems-integration/2.3.0:/usr/share/rubygems-integration/all ruby2.3 -e gem\ \"rspec-rails\"
/usr/lib/ruby/2.3.0/rubygems/dependency.rb:319:in `to_specs': Could not find 'rspec-core' (~> 3.5.0) - did find: [rspec-core-3.7.1] (Gem::LoadError)