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1. hokreb

   added

   BugError, flaw or fault to produce incorrect or unexpected resultsError, flaw or fault to produce incorrect or unexpected results

   on May 17, 2021
2. fleetingbytes commented on Nov 14, 2022

   

   fleetingbytes

   on Nov 14, 2022

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   Similar behavior is also observed with build bumps. A custom build string once set, cannot be reset in a subsequent call of the bump_build method.

   👍React with 👍1Reacted by Tom Schraitle
3. tomschr commented on Nov 23, 2022

   

   tomschr

   on Nov 23, 2022

   Member

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   Yes, this is similar to issue #369.
4. tomschr commented on Mar 5, 2023

   

   tomschr

   on Mar 5, 2023

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   @hokreb Time flies! Sorry for the delay.

   I've tried to confirm it, but if I use the latest version from the master branch, it works:

   >>> import semver
   >>> ver = semver.VersionInfo.parse('1.2.3')
   >>> str(ver.next_version('prerelease', prerelease_token='dev'))
   '1.2.4-dev.1'

   Can you confirm? If yes, I'd like to close this issue. Thanks!
5. Mukller commented on Jul 29, 2026

   

   Mukller

   on Jul 29, 2026

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   Root cause confirmed: bump_prerelease(token, ...) ignores the token parameter when a prerelease already exists.

   Inside bump_prerelease:

   if self._prerelease is not None:
       prerelease = cls._increment_prerelease(self._prerelease)  # token ignored!
   else:
       prerelease = str(token) + '.1'  # token only used for brand-new prerelease

   _increment_prerelease simply finds the trailing number and increments it, so dev.1 → dev.2 regardless of the requested token.

   The maintainer's 2023 confirmation only tested starting from a plain version (1.2.3), where there is no existing prerelease, so the token IS used. The bug reproduces when the token changes between calls:

   import semver
   ver = semver.Version.parse('1.2.3')
   dev1 = ver.next_version('prerelease', prerelease_token='dev')  # 1.2.4-dev.1
   rc1  = dev1.next_version('prerelease', prerelease_token='rc')  # 1.2.4-dev.2 (bug!)
   # expected: 1.2.4-rc.1

   Fix: in next_version, detect when the existing prerelease token differs from the requested one and reset to {new_token}.1 directly:

   if version.prerelease is not None and prerelease_token:
       current_token = version.prerelease.split('.')[0]
       if current_token != prerelease_token:
           return version.replace(prerelease=f'{prerelease_token}.1', build=None)
   return version.bump_prerelease(prerelease_token, bump_when_empty=True)

   I have a PR ready.

   👍React with 👍1Reacted by Tom Schraitle

   🎉React with 🎉1Reacted by Tom Schraitle
6. tomschr

   added a commit that references this issue on Jul 30, 2026

   fix(next_version): reset prerelease when token changes (#339) (#472)

   ...

   fdec4ae
7. tomschr

   closed this as completedin #472on Jul 30, 2026