always qualify boost version

.travis.yml

@@ -59,8 +59,7 @@ jobs:
  - rename
 
  install:
- # it is insufficient to only install boost@1.57 in the first place
- # reinstallation is necessary for some reason
+ # uninstall pre-installed boost and use 1.57
  - brew uninstall --ignore-dependencies boost
  - brew install boost@1.57
  - brew link boost@1.57 --force
@@ -74,8 +73,8 @@ jobs:
  - python ./depends/v8_data_lib.py --multichain $(pwd)
 
  # hide dynamic libraries from the build system so we get a static build
- - rename -e 's/.dylib/.dylib.hidden/' /usr/local/opt/boost/lib/*.dylib
- - rename -e 's/.dylib/.dylib.hidden/' /usr/local/opt/berkeley-db@4/lib/*.dylib
+ - rename -e 's/.dylib/.dylib.hidden/' /usr/local/opt/boost\@1.57/lib/*.dylib
+ - rename -e 's/.dylib/.dylib.hidden/' /usr/local/opt/berkeley-db\@4/lib/*.dylib
 
  # reinstall OpenSSL AFTER reinstalling python, but with static libraries only
  - sed -i '' 's/^ shared$/ no-shared/' /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/openssl.rb
@@ -86,7 +85,7 @@ jobs:
  # disable all warnings to reduce build verbosity
  - export CXXFLAGS=-w
  - ./autogen.sh
- - ./configure --with-gui=no --with-libs=no --with-miniupnpc=no --with-boost=/usr/local/opt/boost@1.57
+ - ./configure --with-gui=no --with-libs=no --with-miniupnpc=no --with-boost=/usr/local/opt/boost\@1.57
  - make -j2
 
  script: