If the version is 1.5b, what is the distribution mechanism?
CREATE TABLE "table1_2263152_1" (
  "version" text,
  "release_date" text,
  "distribution_mechanism" text,
  "features" text,
  "security_issues" text
);
SELECT "distribution_mechanism" FROM "table1_2263152_1" WHERE "version"='1.5b';