Discard un-find-able existing pins in favor of a find-able match. Fixes

jazzband#1530

piptools/repositories/local.py

@@ -10,6 +10,7 @@
 
 from piptools.utils import as_tuple, key_from_ireq, make_install_requirement
 
+from ..exceptions import NoCandidateFound
 from .base import BaseRepository
 from .pypi import PyPIRepository
 
@@ -70,8 +71,13 @@ def find_best_match(
         key = key_from_ireq(ireq)
         existing_pin = self.existing_pins.get(key)
         if existing_pin and ireq_satisfied_by_existing_pin(ireq, existing_pin):
-            project, version, _ = as_tuple(existing_pin)
-            return make_install_requirement(project, version, ireq)
+            try:
+                self.repository.find_best_match(existing_pin, prereleases)
+            except NoCandidateFound:
+                return self.repository.find_best_match(ireq, prereleases)
+            else:
+                project, version, _ = as_tuple(existing_pin)
+                return make_install_requirement(project, version, ireq)
         else:
             return self.repository.find_best_match(ireq, prereleases)
 

tests/test_cli_compile.py

@@ -1620,7 +1620,6 @@ def test_preserve_compiled_prerelease_version(pip_conf, runner):
     assert "small-fake-a==0.3b1" in out.stderr.splitlines()
 
 
-@pytest.mark.xfail
 def test_ignore_compiled_unavailable_version(pip_conf, runner):
     with open("requirements.in", "w") as req_in:
         req_in.write("small-fake-a")