🐛 Fix transaction deadlock in dep builder. (#122)

closes #121 

The `addon.Activity()` reports addon activity which is appended to the
TaskReport.Activity using a PUT. This will briefly acquire a DB
transaction (in the hub).
The builder MUST not report activity because the addon already has a
transaction open in the hub because of the POST of the analysis report.
This creates a DEADLOCK.

**There is a race-condition**: This only happens when the hub begins the
transaction before the dep writer reports the dep.yaml not found. I can
force this by adding a sleep to where the writer reports this. I suspect
the hub can be busy enough with UI GET requests to delay it beginning
the analysis POST until after the builder reports the file not found.

Flow:
```
addon                    hub
   | post analysis ----- >|  
   |                      | begin tx
   | writer <-------------| read 
   | writer: put task --> | begin tx (deadlock)
```

Regression added PR #97

Signed-off-by: Jeff Ortel <[email protected]>

builder/deps.go

@@ -63,7 +63,7 @@ func (b *Deps) read() (input []output.DepsFlatItem, err error) {
 	f, err := os.Open(b.Path)
 	if err != nil {
 		if os.IsNotExist(err) {
-			addon.Activity(err.Error())
+			addon.Log.Info(err.Error())
 			err = nil
 		}
 		return