The current gemspec lists a file that was purposefully ignored (Gemfile.lock). This causes an error for rubygems (and subsequently bundler).
Using sinatra (1.2.0.c) from git://github.com/sinatra/sinatra.git (at master)
sinatra at /path/ did not have a valid gemspec.
This prevents bundler from installing bins or native extensions, but that may not affect its functionality.
The validation message from Rubygems was:
["Gemfile.lock"] are not files
patch (really small so just pasting it here and not doing a pull request):
diff --git a/sinatra.gemspec b/sinatra.gemspec
index 3ed6a90..a1dc9ae 100644
@@ -17,7 +17,6 @@ Gem::Specification.new do |s|
regenerate gemspec, closed by 3e66f67
Signed-off-by: Konstantin Haase <email@example.com>