Rollup merge of #21377 - iKevinY:speedy-tidy, r=huonw
Rollup merge of #21377 - iKevinY:speedy-tidy, r=huonw

`x in y` is more Pythonic than `y.find(x) != -1`. I believe it runs quite a bit faster as well (though it's probably not a bottleneck of the Travis builds):

```bash
$ python -m timeit '"abc".find("a") != -1'
1000000 loops, best of 3: 0.218 usec per loop
$ python -m timeit '"a" in "abc"'
10000000 loops, best of 3: 0.0343 usec per loop
```

dwillmer/rust,cllns/rust,miniupnp/rust,omasanori/rust,mahkoh/rust,defuz/rust,vhbit/rust,mdinger/rust,cllns/rust,jroesch/rust,pelmers/rust,bombless/rust,reem/rust,robertg/rust,gifnksm/rust,victorvde/rust,untitaker/rust,zubron/rust,dwillmer/rust,philyoon/rust,mvdnes/rust,AerialX/rust,mahkoh/rust,l0kod/rust,AerialX/rust-rt-minimal,omasanori/rust,XMPPwocky/rust,l0kod/rust,ruud-v-a/rust,robertg/rust,krzysz00/rust,rohitjoshi/rust,KokaKiwi/rust,aepsil0n/rust,gifnksm/rust,omasanori/rust,carols10cents/rust,zachwick/rust,l0kod/rust,zubron/rust,reem/rust,untitaker/rust,kwantam/rust,pshc/rust,ruud-v-a/rust,GBGamer/rust,AerialX/rust,dwillmer/rust,mahkoh/rust,dwillmer/rust,avdi/rust,avdi/rust,ejjeong/rust,zaeleus/rust,richo/rust,mvdnes/rust,richo/rust,dinfuehr/rust,jroesch/rust,dinfuehr/rust,miniupnp/rust,pshc/rust,aepsil0n/rust,aidancully/rust,rohitjoshi/rust,GBGamer/rust,pshc/rust,robertg/rust,ebfull/rust,cllns/rust,mvdnes/rust,jashank/rust,reem/rust,hauleth/rust,rprichard/rust,GBGamer/rust,zaeleus/rust,omasanori/rust,cllns/rust,jashank/rust,XMPPwocky/rust,mahkoh/rust,zaeleus/rust,seanrivera/rust,aidancully/rust,krzysz00/rust,mihneadb/rust,pshc/rust,philyoon/rust,sae-bom/rust,kwantam/rust,kwantam/rust,avdi/rust,mahkoh/rust,TheNeikos/rust,carols10cents/rust,dwillmer/rust,rprichard/rust,avdi/rust,miniupnp/rust,kwantam/rust,jroesch/rust,nwin/rust,dinfuehr/rust,untitaker/rust,l0kod/rust,rohitjoshi/rust,graydon/rust,jashank/rust,reem/rust,ejjeong/rust,philyoon/rust,mvdnes/rust,pelmers/rust,XMPPwocky/rust,jashank/rust,zubron/rust,rprichard/rust,nwin/rust,jroesch/rust,AerialX/rust-rt-minimal,AerialX/rust-rt-minimal,AerialX/rust-rt-minimal,mihneadb/rust,jroesch/rust,andars/rust,TheNeikos/rust,aneeshusa/rust,dwillmer/rust,zubron/rust,robertg/rust,carols10cents/rust,seanrivera/rust,omasanori/rust,philyoon/rust,carols10cents/rust,jashank/rust,graydon/rust,defuz/rust,defuz/rust,KokaKiwi/rust,nwin/rust,untitaker/rust,victorvde/rust,aidancully/rust,zaeleus/rust,victorvde/rust,nwin/rust,andars/rust,philyoon/rust,miniupnp/rust,ebfull/rust,miniupnp/rust,rohitjoshi/rust,jashank/rust,aneeshusa/rust,defuz/rust,dinfuehr/rust,pshc/rust,GBGamer/rust,nwin/rust,ruud-v-a/rust,AerialX/rust,ruud-v-a/rust,AerialX/rust,ejjeong/rust,aneeshusa/rust,ebfull/rust,rprichard/rust,zachwick/rust,l0kod/rust,dwillmer/rust,bombless/rust,KokaKiwi/rust,mdinger/rust,gifnksm/rust,pelmers/rust,philyoon/rust,reem/rust,l0kod/rust,vhbit/rust,ebfull/rust,aneeshusa/rust,carols10cents/rust,krzysz00/rust,sae-bom/rust,hauleth/rust,vhbit/rust,victorvde/rust,sae-bom/rust,vhbit/rust,pelmers/rust,mdinger/rust,dinfuehr/rust,untitaker/rust,mdinger/rust,cllns/rust,GBGamer/rust,mahkoh/rust,KokaKiwi/rust,jashank/rust,mvdnes/rust,gifnksm/rust,rprichard/rust,rprichard/rust,andars/rust,sae-bom/rust,richo/rust,miniupnp/rust,ebfull/rust,seanrivera/rust,zachwick/rust,mihneadb/rust,untitaker/rust,KokaKiwi/rust,hauleth/rust,sae-bom/rust,mdinger/rust,jroesch/rust,pelmers/rust,graydon/rust,rohitjoshi/rust,XMPPwocky/rust,GBGamer/rust,TheNeikos/rust,hauleth/rust,zubron/rust,pshc/rust,robertg/rust,mihneadb/rust,bombless/rust,seanrivera/rust,AerialX/rust,TheNeikos/rust,graydon/rust,richo/rust,mihneadb/rust,gifnksm/rust,hauleth/rust,krzysz00/rust,AerialX/rust,TheNeikos/rust,miniupnp/rust,dwillmer/rust,zubron/rust,avdi/rust,mvdnes/rust,AerialX/rust-rt-minimal,carols10cents/rust,aidancully/rust,zaeleus/rust,andars/rust,richo/rust,ejjeong/rust,l0kod/rust,AerialX/rust-rt-minimal,zaeleus/rust,GBGamer/rust,hauleth/rust,zachwick/rust,jroesch/rust,victorvde/rust,bombless/rust,bombless/rust,aneeshusa/rust,sae-bom/rust,victorvde/rust,reem/rust,mdinger/rust,miniupnp/rust,nwin/rust,dinfuehr/rust,pelmers/rust,andars/rust,ejjeong/rust,pshc/rust,ebfull/rust,robertg/rust,zubron/rust,XMPPwocky/rust,pshc/rust,TheNeikos/rust,krzysz00/rust,krzysz00/rust,defuz/rust,KokaKiwi/rust,richo/rust,aepsil0n/rust,vhbit/rust,kwantam/rust,omasanori/rust,aidancully/rust,zachwick/rust,seanrivera/rust,seanrivera/rust,jashank/rust,ruud-v-a/rust,vhbit/rust,aidancully/rust,zubron/rust,l0kod/rust,jroesch/rust,vhbit/rust,defuz/rust,andars/rust,graydon/rust,bombless/rust,aepsil0n/rust,kwantam/rust,avdi/rust,cllns/rust,nwin/rust,zachwick/rust,aepsil0n/rust,mihneadb/rust,ruud-v-a/rust,aneeshusa/rust,rohitjoshi/rust,ejjeong/rust,XMPPwocky/rust,gifnksm/rust,aepsil0n/rust,graydon/rust,nwin/rust,vhbit/rust,GBGamer/rust