com.github.mpeltonen#sbt-idea;1.7.0-SNAPSHOT: not found

[martende]

I have written some simple test project with build.sbt

name := "a1"

version := "1.0"

scalaVersion := "2.11.8"

// try to repair com.github.mpeltonen#sbt-idea;1.7.0-SNAPSHOT: not found

resolvers in ThisBuild += "Sonatype snapshots" at "https://oss.sonatype.org/content/repositories/snapshots/"

lazy val a2 = RootProject(file("../a2"))

lazy val root = (project in file(".")).dependsOn(a2)

a2 is the other external project ( also just one file and dummy sbt )

if i am using sbt from cmd line evrething is fine . but in Idea i am seeing sbt error if i am using sbt plugin.

SBT 'a1' project refresh failed
    Error:Error:Error while importing SBT project:<br/>...<br/><pre>[info] Resolving org.scala-sbt#precompiled-2_9_3;0.13.8 ...
[info] Resolving com.github.mpeltonen#sbt-idea;1.7.0-SNAPSHOT ...
[info] Resolving com.github.mpeltonen#sbt-idea;1.7.0-SNAPSHOT ...
[info] Resolving commons-io#commons-io;2.4 ...
[info] Resolving org.scala-lang#scala-library;2.11.8 ...
[info] Resolving org.scala-lang#scala-compiler;2.11.8 ...
[info] Resolving org.scala-lang#scala-reflect;2.11.8 ...
[info] Resolving org.scala-lang.modules#scala-xml_2.11;1.0.4 ...
[info] Resolving org.scala-lang.modules#scala-parser-combinators_2.11;1.0.4 ...
[info] Resolving jline#jline;2.12.1 ...
[info] Resolving org.scala-lang#scala-library;2.11.8 ...
[info] Resolving default#a2_2.11;1.0 ...
[info] Resolving org.scala-lang#scala-compiler;2.11.8 ...
[info] Resolving org.scala-lang#scala-reflect;2.11.8 ...
[info] Resolving org.scala-lang.modules#scala-xml_2.11;1.0.4 ...
[info] Resolving org.scala-lang.modules#scala-parser-combinators_2.11;1.0.4 ...
[info] Resolving jline#jline;2.12.1 ...
[trace] Stack trace suppressed: run 'last {file:/home/user/MProg/TMP/a2/}a2/*:updateSbtClassifiers' for the full output.
[error] ({file:/home/user/MProg/TMP/a2/}a2/*:updateSbtClassifiers) sbt.ResolveException: unresolved dependency: com.github.mpeltonen#sbt-idea;1.7.0-SNAPSHOT: not found
[error] Total time: 4 s, completed Aug 9, 2016 8:30:35 PM</pre><br/>See complete log in <a href="/home/user/.IdeaIC2016.1/system/log/sbt.last.log">/home/belka2/.IdeaIC2016.1/system/log/sbt.last.log</a>

if I remove dependency from a2 - everething works fine.

I have some questions :

1. what sbt command is called during this stage and how can i simulate it in shell ?
2. why com.github.mpeltonen#sbt-idea is not found
3. and why it is even resolved

Thank You.