Auto merge of #6211 - papanikge:add-source-when-failing, r=segiddins

Add explicit source when available in the error msg upon failure

### What was the end-user problem that led to this PR?

My bundling failed and the command that `bundler` output was wrong-ish, in the sense that my gem was suppose to come from a different source.

### What was your diagnosis of the problem?

The error message was not explicit.

### What is your fix for the problem, implemented in this PR?

Bundler now explicitly print the source when there's just one. I think it's a good case just to print it when there's one. If there are more it's ambiguous, so we fallback to the old way. Maybe we could have a warning there that the command might not be exactly what the user wants.

### Why did you choose this fix out of the possible options?

See previous answer. I didn't find any easier ways of getting the source url.
Let me know if there are better implementations :)

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/bundler/installer/gem_installer.rb b/lib/bundler/installer/gem_installer.rb
index 086b763d20..a38f8d95be 100644
--- a/lib/bundler/installer/gem_installer.rb
+++ b/lib/bundler/installer/gem_installer.rb
@@ -44,7 +44,12 @@ module Bundler
     end
 
     def gem_install_message
-      "Make sure that `gem install #{spec.name} -v '#{spec.version}'` succeeds before bundling."
+      remotes = spec.source.remotes
+      if remotes.size == 1
+        "Make sure that `gem install #{spec.name} -v '#{spec.version}' --source '#{remotes.first}'` succeeds before bundling."
+      else
+        "Make sure that `gem install #{spec.name} -v '#{spec.version}'` succeeds before bundling."
+      end
     end
 
     def spec_settings