Tests: Simplify CTest.UpdateGIT repo path construction

Avoid constructing full paths to .git repositories in the test.  Use
relative paths and let Git convert them to absolute paths internally.
This is simpler and also avoids trouble with various absolute path root
component conventions on Windows (`c:/`, `/c/`, `/cygdrive/c/`).

Tests/CTestUpdateGIT.cmake.in

@@ -41,7 +41,6 @@ run_child(
   COMMAND ${GIT} --bare init
   )
 file(REMOVE_RECURSE ${TOP}/repo.git/hooks)
-set(REPO file://${TOP}/repo.git)
 
 # Create submodule repository.
 message("Creating submodule...")
@@ -51,17 +50,13 @@ run_child(
   COMMAND ${GIT} --bare init
   )
 file(REMOVE_RECURSE ${TOP}/module.git/hooks)
-set(MOD_REPO file://${TOP}/module.git)
-create_content(module)
-run_child(WORKING_DIRECTORY ${TOP}/module
-  COMMAND ${GIT} init
+run_child(WORKING_DIRECTORY ${TOP}
+  COMMAND ${GIT} clone module.git module
   )
 file(REMOVE_RECURSE ${TOP}/module/.git/hooks)
 file(APPEND ${TOP}/module/.git/config "
-[remote \"origin\"]
-\turl = ${MOD_REPO}
-\tfetch = +refs/heads/*:refs/remotes/origin/*
 ${AUTHOR_CONFIG}")
+create_content(module)
 run_child(WORKING_DIRECTORY ${TOP}/module
   COMMAND ${GIT} add .
   )
@@ -75,20 +70,17 @@ run_child(WORKING_DIRECTORY ${TOP}/module
 #-----------------------------------------------------------------------------
 # Import initial content into the repository.
 message("Importing content...")
-create_content(import)
-file(WRITE ${TOP}/import/HEAD "HEAD\n")
-file(WRITE ${TOP}/import/master "master\n")
 
 # Import the content into the repository.
-run_child(WORKING_DIRECTORY ${TOP}/import
-  COMMAND ${GIT} init
+run_child(WORKING_DIRECTORY ${TOP}
+  COMMAND ${GIT} clone repo.git import
   )
 file(REMOVE_RECURSE ${TOP}/import/.git/hooks)
 file(APPEND ${TOP}/import/.git/config "
-[remote \"origin\"]
-\turl = ${REPO}
-\tfetch = +refs/heads/*:refs/remotes/origin/*
 ${AUTHOR_CONFIG}")
+create_content(import)
+file(WRITE ${TOP}/import/HEAD "HEAD\n")
+file(WRITE ${TOP}/import/master "master\n")
 run_child(WORKING_DIRECTORY ${TOP}/import
   COMMAND ${GIT} add .
   )
@@ -96,7 +88,7 @@ run_child(WORKING_DIRECTORY ${TOP}/import
   COMMAND ${GIT} config core.safecrlf false
   )
 run_child(WORKING_DIRECTORY ${TOP}/import
-  COMMAND ${GIT} submodule add ${MOD_REPO} module
+  COMMAND ${GIT} submodule add ../module.git module
   )
 run_child(WORKING_DIRECTORY ${TOP}/import
   COMMAND ${GIT} commit -m "Initial content"
@@ -123,7 +115,7 @@ run_child(WORKING_DIRECTORY ${TOP}/module
 message("Checking out revision 1...")
 run_child(
   WORKING_DIRECTORY ${TOP}
-  COMMAND ${GIT} clone ${REPO} user-source
+  COMMAND ${GIT} clone repo.git user-source
   )
 file(REMOVE_RECURSE ${TOP}/user-source/.git/hooks)
 file(APPEND ${TOP}/user-source/.git/config "${AUTHOR_CONFIG}")
@@ -278,7 +270,7 @@ set(CTEST_GIT_COMMAND \"${GIT}\")
 set(CTEST_GIT_UPDATE_OPTIONS)
 execute_process(
   WORKING_DIRECTORY \"${TOP}\"
-  COMMAND \"${GIT}\" clone \"${REPO}\" dash-source
+  COMMAND \"${GIT}\" clone repo.git dash-source
   )
 
 # Test .git file.