fix: avoid clobbering sh: vars when resolving global Ref values

[JonZeolla]

Summary

• Fixes a regression in v3.49.0 where global sh: variables resolve to empty strings when the Taskfile has includes:
• The ReplaceVars call added in fix: Call ReplaceVars() to resolve Ref's for imported global vars. #2632 now only processes variables with Ref values set, leaving already-resolved sh: variables untouched
• Adds test case covering sh: dynamic vars with included Taskfiles

Root Cause

The ReplaceVars call on line 118 of compiler.go re-processes all TaskfileVars after they've been resolved by rangeFunc. For sh: variables, ReplaceVarWithExtra returns a new Var with the original Sh string but nil Value, destroying the already-resolved result.

Test plan

• Added TestShVarWithIncludes with golden file asserting sh: vars resolve correctly alongside includes
• Verified test fails before fix (TDD red phase): DERIVED_VAR= world
• Verified test passes after fix (TDD green phase): DERIVED_VAR=hello world
• All existing TestReference subtests still pass (including ref-global from fix: Call ReplaceVars() to resolve Ref's for imported global vars. #2632)
• Full test suite passes

Fixes #2720

[Copilot]

Pull request overview

Fixes a regression where global sh: vars could be overwritten during post-processing of global variables when a Taskfile contains includes:.

Changes:

• Adjusts global variable post-processing in Compiler.getVariables to only resolve globals with Ref set.
• Adds an executor test plus new fixture Taskfiles/golden output to cover sh: vars with includes.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
compiler.go	Changes global-var post-pass to resolve only Ref globals (avoiding sh: clobber).
executor_test.go	Adds TestShVarWithIncludes to exercise the regression scenario.
testdata/var_sh_with_includes/Taskfile.yml	New fixture Taskfile defining global sh: and derived vars plus an include.
testdata/var_sh_with_includes/Included.yml	Included fixture Taskfile to trigger include handling.
testdata/var_sh_with_includes/testdata/TestShVarWithIncludes-sh_var_not_clobbered_by_includes.golden	Golden output asserting sh: + derived var values remain correct.

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[Copilot]

This loop resolves Ref values by mutating c.TaskfileVars, but it never updates the result Vars map that getVariables returns and that is used for templating later in the same call. If a global ref: var failed to resolve in the first pass due to ordering (the regression fixed in #2632), it will still be nil/empty in result for the current execution. Consider also writing the resolved value back into result (and resetting the templater cache if needed), or performing a second evaluation pass that repopulates result from the updated global vars.

Suggested change

	c.TaskfileVars.Set(k, ast.Var{Value: templater.ResolveRef(v.Ref, cache)})
	resolved := templater.ResolveRef(v.Ref, cache)
	c.TaskfileVars.Set(k, ast.Var{Value: resolved})
	result.Set(k, ast.Var{Value: resolved})