Add comments to ActiveSupport::Dependencies to help understanding
Add comments to ActiveSupport::Dependencies to help understanding

In a previous patch, all log-related stuff was removed. However,
some logs are still useful to understand the code. Therefore, in
this patch, I put those log messages back as comments.

[ci skip]

kddeisz/rails,ngpestelos/rails,kmcphillips/rails,arunagw/rails,Vasfed/rails,alecspopa/rails,gauravtiwari/rails,bradleypriest/rails,gcourtemanche/rails,untidy-hair/rails,bolek/rails,BlakeWilliams/rails,rossta/rails,vipulnsward/rails,kaspth/rails,deraru/rails,mathieujobin/reduced-rails-for-travis,repinel/rails,georgeclaghorn/rails,maicher/rails,gcourtemanche/rails,illacceptanything/illacceptanything,eileencodes/rails,printercu/rails,gavingmiller/rails,mtsmfm/railstest,EmmaB/rails-1,illacceptanything/illacceptanything,esparta/rails,riseshia/railsguides.kr,tgxworld/rails,kenta-s/rails,amoody2108/TechForJustice,yhirano55/rails,kddeisz/rails,lcreid/rails,iainbeeston/rails,tgxworld/rails,voray/rails,sergey-alekseev/rails,matrinox/rails,palkan/rails,stefanmb/rails,Vasfed/rails,MSP-Greg/rails,xlymian/rails,Envek/rails,iainbeeston/rails,yawboakye/rails,odedniv/rails,Envek/rails,palkan/rails,arunagw/rails,yawboakye/rails,maicher/rails,maicher/rails,illacceptanything/illacceptanything,repinel/rails,mathieujobin/reduced-rails-for-travis,vipulnsward/rails,sealocal/rails,marklocklear/rails,rails/rails,koic/rails,arunagw/rails,gcourtemanche/rails,marklocklear/rails,mohitnatoo/rails,hanystudy/rails,ttanimichi/rails,Edouard-chin/rails,mtsmfm/rails,tgxworld/rails,bogdanvlviv/rails,travisofthenorth/rails,felipecvo/rails,yalab/rails,baerjam/rails,alecspopa/rails,illacceptanything/illacceptanything,mtsmfm/rails,gavingmiller/rails,mohitnatoo/rails,palkan/rails,eileencodes/rails,stefanmb/rails,baerjam/rails,Sen-Zhang/rails,yasslab/railsguides.jp,riseshia/railsguides.kr,kachick/rails,amoody2108/TechForJustice,illacceptanything/illacceptanything,baerjam/rails,rafaelfranca/omg-rails,tijwelch/rails,betesh/rails,BlakeWilliams/rails,tjschuck/rails,tijwelch/rails,Erol/rails,gauravtiwari/rails,georgeclaghorn/rails,mtsmfm/rails,aditya-kapoor/rails,voray/rails,hanystudy/rails,palkan/rails,prathamesh-sonpatki/rails,bradleypriest/rails,lcreid/rails,kenta-s/rails,sergey-alekseev/rails,fabianoleittes/rails,untidy-hair/rails,eileencodes/rails,mijoharas/rails,ttanimichi/rails,coreyward/rails,coreyward/rails,yawboakye/rails,Edouard-chin/rails,utilum/rails,untidy-hair/rails,yhirano55/rails,notapatch/rails,kirs/rails-1,jeremy/rails,iainbeeston/rails,flanger001/rails,richseviora/rails,prathamesh-sonpatki/rails,matrinox/rails,arjes/rails,mijoharas/rails,esparta/rails,bogdanvlviv/rails,prathamesh-sonpatki/rails,lcreid/rails,sergey-alekseev/rails,shioyama/rails,utilum/rails,jeremy/rails,arjes/rails,assain/rails,voray/rails,kmcphillips/rails,yahonda/rails,illacceptanything/illacceptanything,kenta-s/rails,pvalena/rails,kaspth/rails,Envek/rails,tjschuck/rails,Vasfed/rails,xlymian/rails,notapatch/rails,starknx/rails,lucasmazza/rails,Stellenticket/rails,kachick/rails,yalab/rails,yalab/rails,joonyou/rails,kachick/rails,mathieujobin/reduced-rails-for-travis,alecspopa/rails,ttanimichi/rails,flanger001/rails,schuetzm/rails,rails/rails,vassilevsky/rails,MichaelSp/rails,pvalena/rails,BlakeWilliams/rails,kirs/rails-1,MSP-Greg/rails,betesh/rails,bogdanvlviv/rails,assain/rails,illacceptanything/illacceptanything,rafaelfranca/omg-rails,deraru/rails,kamipo/rails,stefanmb/rails,elfassy/rails,lcreid/rails,mohitnatoo/rails,sealocal/rails,flanger001/rails,tgxworld/rails,travisofthenorth/rails,riseshia/railsguides.kr,fabianoleittes/rails,rbhitchcock/rails,Spin42/rails,EmmaB/rails-1,amoody2108/TechForJustice,Edouard-chin/rails,fabianoleittes/rails,Sen-Zhang/rails,sealocal/rails,gfvcastro/rails,illacceptanything/illacceptanything,illacceptanything/illacceptanything,esparta/rails,yahonda/rails,ledestin/rails,Spin42/rails,yawboakye/rails,schuetzm/rails,mechanicles/rails,samphilipd/rails,ngpestelos/rails,coreyward/rails,samphilipd/rails,koic/rails,Erol/rails,printercu/rails,odedniv/rails,brchristian/rails,felipecvo/rails,assain/rails,elfassy/rails,pschambacher/rails,Vasfed/rails,bolek/rails,mijoharas/rails,gfvcastro/rails,kmcphillips/rails,riseshia/railsguides.kr,betesh/rails,illacceptanything/illacceptanything,rossta/rails,utilum/rails,deraru/rails,aditya-kapoor/rails,richseviora/rails,EmmaB/rails-1,repinel/rails,eileencodes/rails,Envek/rails,pschambacher/rails,betesh/rails,illacceptanything/illacceptanything,Erol/rails,kaspth/rails,Erol/rails,yahonda/rails,shioyama/rails,samphilipd/rails,arjes/rails,repinel/rails,richseviora/rails,yasslab/railsguides.jp,kmayer/rails,illacceptanything/illacceptanything,lucasmazza/rails,rails/rails,MichaelSp/rails,aditya-kapoor/rails,vassilevsky/rails,deraru/rails,baerjam/rails,joonyou/rails,travisofthenorth/rails,schuetzm/rails,gavingmiller/rails,ledestin/rails,printercu/rails,assain/rails,shioyama/rails,yalab/rails,joonyou/rails,kddeisz/rails,illacceptanything/illacceptanything,Sen-Zhang/rails,rafaelfranca/omg-rails,MichaelSp/rails,mechanicles/rails,odedniv/rails,lucasmazza/rails,yhirano55/rails,pschambacher/rails,utilum/rails,brchristian/rails,mechanicles/rails,pvalena/rails,Spin42/rails,mtsmfm/railstest,kamipo/rails,hanystudy/rails,iainbeest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