More fixes to git stash when bumping version

Author: angularsen

Build/set-version-UnitsNet.ps1

@@ -61,7 +61,7 @@ $winrtNuspecFile = "$root\UnitsNet.WindowsRuntimeComponent\UnitsNet.WindowsRunti
 $newVersion = Get-NewProjectVersion $projFile $paramSet $setVersion $bumpVersion
 
 # Reset and stash any other local changes.
-Invoke-StashPush
+$didStash = Invoke-StashPush
 
 # Update project files
 Set-ProjectVersion $projFile $newVersion
@@ -79,4 +79,6 @@ Invoke-CommitVersionBump @("UnitsNet") $newVersion
 Invoke-TagVersionBump "UnitsNet" $newVersion
 
 # Restore any local changes.
-Invoke-StashPop
+if ($didStash) {
+  Invoke-StashPop
+}

Build/set-version.psm1

@@ -17,8 +17,11 @@ function Get-NewProjectVersion(
 }
 
 function Invoke-StashPush() {
+  $oldSha=$(git rev-parse -q --verify refs/stash)
   git reset --quiet
-  git stash --include-untracked --message "Before version bump" --quiet
+  git stash push --include-untracked --message "Before version bump" --quiet
+  $newSha=$(git rev-parse -q --verify refs/stash)
+  return $oldSha -ne $newSha
 }
 
 function Invoke-StashPop() {