Generate logs in verbose mode

Closes Homebrew/homebrew#23654.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/formula.rb

@@ -567,9 +567,6 @@ class Formula
       ENV.remove_cc_etc
     end
 
-    if ARGV.verbose?
-      safe_system cmd, *args
-    else
     @exec_count ||= 0
     @exec_count += 1
     logd = HOMEBREW_LOGS/name
@@ -589,20 +586,22 @@ class Formula
     wr.close
 
     File.open(logfn, 'w') do |f|
-        f.write(rd.read) until rd.eof?
+      while buf = rd.gets
+        f.puts buf
+        puts buf if ARGV.verbose?
+      end
 
       Process.wait
 
       unless $?.success?
         f.flush
-          Kernel.system "/usr/bin/tail", "-n", "5", logfn
+        Kernel.system "/usr/bin/tail", "-n", "5", logfn unless ARGV.verbose?
         f.puts
         require 'cmd/--config'
         Homebrew.write_build_config(f)
         raise ErrorDuringExecution
       end
     end
-    end
   rescue ErrorDuringExecution
     raise BuildError.new(self, cmd, args, $?)
   ensure