`echo outdated` shows `zstd` which can't be upgraded

[catap (Kirill A. Korinsky)]

√ ~ % port echo outdated
zstd                           @1.5.0_0 
√ ~ % sudo port upgrade outdated
Password:
--->  Scanning binaries for linking errors
--->  No broken files found.                             
--->  No broken ports found.
√ ~ % port echo outdated        
zstd                           @1.5.0_0 
√ ~ % sudo port upgrade outdated
--->  Scanning binaries for linking errors
--->  No broken files found.                             
--->  No broken ports found.
√ ~ % sudo port upgrade zstd    
--->  Scanning binaries for linking errors
--->  No broken files found.                             
--->  No broken ports found.
√ ~ % port echo outdated        
zstd                           @1.5.0_0 
√ ~ % sudo port uninstall zstd       
Note: It is not recommended to uninstall/deactivate a port that has dependents as it breaks the dependents.
The following ports will break:
 curl @7.80.0_0
 libarchive @3.5.2_0
 rsync @3.2.3_1
 boost176 @1.76.0_2
 tiff @4.3.0_0
 ccache @4.5.1_0
 qt5-qtbase @5.15.2_4
Continue? [y/N]: y
Warning: Uninstall forced.  Proceeding despite dependencies.
--->  Deactivating zstd @1.5.0_0
--->  Cleaning zstd
--->  Uninstalling zstd @1.5.0_0
--->  Cleaning zstd
√ ~ % port echo outdated      
√ ~ % sudo port install --unrequested zstd
--->  Computing dependencies for zstd
--->  Fetching archive for zstd
--->  Attempting to fetch zstd-1.5.0_0.darwin_21.x86_64.tbz2 from https://fra.de.packages.macports.org/zstd
--->  Attempting to fetch zstd-1.5.0_0.darwin_21.x86_64.tbz2.rmd160 from https://fra.de.packages.macports.org/zstd
--->  Installing zstd @1.5.0_0
--->  Activating zstd @1.5.0_0
--->  Cleaning zstd
--->  Scanning binaries for linking errors
--->  No broken files found.                             
--->  No broken ports found.
√ ~ % port echo outdated                  
zstd                           @1.5.0_0 
√ ~ % sudo port upgrade zstd              
--->  Scanning binaries for linking errors
--->  No broken files found.                             
--->  No broken ports found.
√ ~ % 

[ryandesign (Ryan Carsten Schmidt)]

Delete your PortIndex and PortIndex.quick and let MacPorts recreate them.

See ​https://lists.macports.org/pipermail/macports-dev/2021-October/043840.html

[ryandesign (Ryan Carsten Schmidt)]

Duplicate of #63685.