fixes #10273 execShellCmd now returns nonzero when child killed with signal + other fixes (#10274)

* s/exitStatus(...)/exitStatusLikeShell(...)/
* fix #10273 execShellCmd now returns nonzero when child exits with signal
* test case for #10249 and explanation for the bug
* fix test failure
* add tests/nim.cfg

testament/lib/stdtest/specialpaths.nim

@@ -0,0 +1,31 @@
+#[
+todo: move findNimStdLibCompileTime, findNimStdLib here
+]#
+
+import os
+
+# Note: all the const paths defined here are known at compile time and valid
+# so long Nim repo isn't relocated after compilation.
+# This means the binaries they produce will embed hardcoded paths, which
+# isn't appropriate for some applications that need to be relocatable.
+
+const sourcePath = currentSourcePath()
+  # robust way to derive other paths here
+  # We don't depend on PATH so this is robust to having multiple nim
+  # binaries
+
+const nimRootDir* = sourcePath.parentDir.parentDir.parentDir.parentDir
+  ## root of Nim repo
+
+const stdlibDir* = nimRootDir / "lib"
+  # todo: make nimeval.findNimStdLibCompileTime use this
+
+const systemPath* = stdlibDir / "system.nim"
+
+const buildDir* = nimRootDir / "build"
+  ## refs #10268: all testament generated files should go here to avoid
+  ## polluting .gitignore
+
+static:
+  # sanity check
+  doAssert fileExists(systemPath)