Fix GitVersionTask on Linux

The additional import statement introduced in #1163 causes failure
on Linux when a project tries to use the GitVersionTask. It seems
that Mono can't cope with an empty `Project` attribute in the
`Import` element. Additionally there seems to be a bug at least in
Mono 3.x in that it requires the argument in `Exists` to be passed
in quotes.

This change fixes these two problems and allows to use the
GitVersionTask again on Linux.

Author: ermshiperete

src/GitVersionTask/NugetAssets/build/GitVersionTask.targets

@@ -9,6 +9,7 @@
     <GitVersionPath Condition="'$(GitVersionPath)' == ''">$(MSBuildProjectDirectory)</GitVersionPath>
     <GitVersionCustomizeTargetFile Condition="'$(GitVersionCustomizeTargetFile)' == '' And Exists('$(MSBuildProjectDirectory)\GitVersionTask.targets')">$(SolutionDir)\GitVersionTask.targets</GitVersionCustomizeTargetFile>
     <GitVersionCustomizeTargetFile Condition="'$(GitVersionCustomizeTargetFile)' == '' And '$(SolutionDir)' != '' And Exists('$(SolutionDir)\GitVersionTask.targets')">$(SolutionDir)\GitVersionTask.targets</GitVersionCustomizeTargetFile>
+    <GitVersionCustomizeTargetFile Condition="'$(GitVersionCustomizeTargetFile)' == ''"></GitVersionCustomizeTargetFile>
     <IntermediateOutputPath Condition="$(IntermediateOutputPath) == '' Or $(IntermediateOutputPath) == '*Undefined*'">$(MSBuildProjectDirectory)\obj\$(Configuration)\</IntermediateOutputPath>
     <GitVersion_NoFetchEnabled Condition="$(GitVersion_NoFetchEnabled) == ''">false</GitVersion_NoFetchEnabled>
 
@@ -39,7 +40,7 @@
       TaskName="GitVersionTask.WriteVersionInfoToBuildLog"
       AssemblyFile="$(GitVersionTaskLibrary)GitVersionTask.dll" />
 
-  <Import Project="$(GitVersionCustomizeTargetFile)" Condition="'$(GitVersionCustomizeTargetFile)' != '' and Exists($(GitVersionCustomizeTargetFile))" />
+  <Import Project="$(GitVersionCustomizeTargetFile)" Condition="'$(GitVersionCustomizeTargetFile)' != '' and Exists('$(GitVersionCustomizeTargetFile)')" />
 
   <Target Name="WriteVersionInfoToBuildLog" BeforeTargets="CoreCompile;GetAssemblyVersion;GenerateNuspec" Condition="$(WriteVersionInfoToBuildLog) == 'true'">
     <WriteVersionInfoToBuildLog SolutionDirectory="$(GitVersionPath)" NoFetch="$(GitVersion_NoFetchEnabled)"/>
@@ -119,4 +120,4 @@
     </None>
   </ItemGroup>
 
-</Project>
+</Project>

src/GitVersionTask/NugetAssets/buildMultiTargeting/GitVersionTask.targets

@@ -9,6 +9,7 @@
     <GitVersionPath Condition="'$(GitVersionPath)' == ''">$(MSBuildProjectDirectory)</GitVersionPath>
     <GitVersionCustomizeTargetFile Condition="'$(GitVersionCustomizeTargetFile)' == '' And Exists('$(MSBuildProjectDirectory)\GitVersionTask.targets')">$(SolutionDir)\GitVersionTask.targets</GitVersionCustomizeTargetFile>
     <GitVersionCustomizeTargetFile Condition="'$(GitVersionCustomizeTargetFile)' == '' And '$(SolutionDir)' != '' And Exists('$(SolutionDir)\GitVersionTask.targets')">$(SolutionDir)\GitVersionTask.targets</GitVersionCustomizeTargetFile>
+    <GitVersionCustomizeTargetFile Condition="'$(GitVersionCustomizeTargetFile)' == ''"></GitVersionCustomizeTargetFile>
     <GitVersion_NoFetchEnabled Condition="$(GitVersion_NoFetchEnabled) == ''">false</GitVersion_NoFetchEnabled>
 
     <!-- Property that enables WriteVersionInfoToBuildLog -->
@@ -37,7 +38,7 @@
       TaskName="GitVersionTask.WriteVersionInfoToBuildLog"
       AssemblyFile="$(GitVersionTaskLibrary)GitVersionTask.dll" />
 
-  <Import Project="$(GitVersionCustomizeTargetFile)" Condition="'$(GitVersionCustomizeTargetFile)' != '' and Exists($(GitVersionCustomizeTargetFile))" />
+  <Import Project="$(GitVersionCustomizeTargetFile)" Condition="'$(GitVersionCustomizeTargetFile)' != '' and Exists('$(GitVersionCustomizeTargetFile)')" />
 
   <Target Name="WriteVersionInfoToBuildLog" BeforeTargets="DispatchToInnerBuilds;GenerateNuspec" Condition="$(WriteVersionInfoToBuildLog) == 'true'">
     <WriteVersionInfoToBuildLog SolutionDirectory="$(GitVersionPath)" NoFetch="$(GitVersion_NoFetchEnabled)"/>
@@ -85,4 +86,4 @@
     </PropertyGroup>
 
   </Target>
-</Project>
+</Project>